The Throwing Power Of Oddcomp(z)


by

Huen Y.K.

CAHRC, P.O.Box 1003, Singapore 911101
http://web.singnet.com.sg/~huens/
email: huens@mbox3.singnet.com.sg

(A short communication - 1st released: 24/9/97. Revision: 25/9,27/9 )


Abstract

The Throwing Power of a sequence algebraic generating function is defined as the number of periodic Z/i layers required to generate a finite contiguous sequence correctly without any misses in between. For example, it is well known that if k layers are taken in Comp(z) the number of correct terms predicted is approximately 2*k [1,4 to 9]. Thus the throwing power of Comp(z) is 2 which is rather low. It was discovered recently by the author that Oddcomp(z) has much higher throwing power than Comp(z), approximately 85 times in the numerical investigations reported in this paper. This makes Oddcomp(z) a much better candidate for computing Prime(z) via the identity of Odd(z) - Normc(Oddcomp(z)) considering that we only need to consider odd integers in computations. Due to limitation in computing resources, no attempt has been made to investigate beyond 10000 terms using a symbolic package. However, the author conjectures that the throwing power of Oddcomp(z) might even increase proportionally in the large integer range due to the fact that the density of Oddcomp(z) terms actually increases at the expense of Prime(z) terms. Detailed performance of Oddcomp(z) certainly warrants more numerical studies. There is as yet no theoretical method of predicting throwing power of generating functions although a deterministic global expression for Oddcomp(z) has already been developed [5].


1. Introduction


The term throwing power is borrowed from the electroplating industry which measures the weight of plating metal deposited per watt of power expanded. An analogy can also be drawn between two shot-putters if the distance of the throw per kg of body weight is used as a measure of throwing efficiency. Applied to sequence algebraic generating functions, it is defined to mean the number of contiguous correct terms predicted by a generating function measured against the number of Z/i layers used in the computation. To explain this let us use the now familiar equation of divisibles given by equation (1) [7]:

..............................................upperbound
...............................................-----
............................................... \...............1
..........................Comp(z) :=.....)........----------- ..........................................(1).
................................................/.............i....i
...............................................----- ....z..(z - 1)
................................................i = 2

For each fixed value of i, we call the expression contained within the summation sign in equation (1) a Z/i layer. Normally, to compute 100 correct terms in Comp(z), the upperbound of i should be set to 100. However, from knowledge of periodicities of summated sequences, we know that evem of half the Z/i layers are used, i.e. i=2..50, the composite number sequence will still be correct up to the full range albeit that the numerator coefficients in the upperhalf of the sequence will be smaller. Since we are only interested in the composites themselves, the errors in these coefficients are not that important. Hence by the definition of throwing power, Comp(z) has a throwing power of 100/50 = 2.

The formula for Oddcomp(z) has already been previously developed [5]. In this paper, the throwing power of Oddcomp(z) is investigated. It is known that if Oddcomp(z) is fully expanded starting from i = 1, it will predict deterministically the odd composite sequence but this demands considerable computing resources. Since most of the time such a sequence would be normalised using Normc( ), we could have ignored the accuracy of the numerator coefficients or duplicity factors. Oddcomp1(z) is expanded using the range of i = 1..10000 for computations which will ensure that all odd composite terms in the sequence are correct. This will be used to benchmark an Oddcomp2(z) sequence which is similarly expanded using i = 1..40. The expansions are term by term compared in order to discover at what point will the first miss occur in the Oddcomp(z0 sequence.


2. The Test Procedures

Step(1): We expand Oddcomp(z) by Maple V R 3 to 10000 terms using equation (2).

Oddcomp1(z):=sort(series(sum(1/(z^(2*i+1)*(z^(2*(2*i+1))-1)),i=1..10000), z=infinity,10000)); ..........................................................................(2).

The expansions are only partially recorded for page economy. Note that the integer 6889 written in bold font is the first oddcomposite integer missing in Oddcomp2(z) of equations (4) and (5).


.................................1..........1.........2.......2.......1.......2.......2.......2.......2......4.......1.......2.......2
Oddcomp1(z) := O(------) + ---- + --- + --- + --- + --- + --- + --- + --- + --- + --- + --- + ---
................................10001.....9.......15......21.....25.....27.....33.....35.....39.....45.....49.....51....55
...............................z.............z.........z........z.......z.......z........z.......z........z.......z.......z.......z.......z

....2......4........2.......2.......4.......2.......3.......2.......2......2......2......2........4........6........2
+ --- + --- + --- + --- + --- + --- + --- + --- + --- + --- + --- + --- + --- + ---- + ----
.....57.....63.....65......69....75.....77.....81.....85.....87....91....93.....95.....99....105......111
....z.......z.......z........z........z........z.......z.......z........z......z......z........z.......z.......z..........z

+.....................................................................................................+......

.....6..........2.........2.........2..........10.........6..........8..........4...........2.........2........18.........2
+ ----- + ----- + ----- + ----- + ----- + ----- + ----- + ----- + ----- + ----- + ----- + -----
...6855.....6859....6861...6865....6867...6873...6875....6877....6879....6881....6885....6887
..z............z..........z.........z..........z..........z..........z...........z...........z...........z..........z..........z

.....1..........2.........2.........6..........10..........2.........10........2...........10........2.........6..........6
+ ----- + ----- + ----- + ----- + ----- + ----- + ----- + ----- + ----- + ----- + ----- + -----
...6889....6891....6893....6895....6897....6901....6903....6905....6909....6913....6915....6919
..z...........z...........z.........z..........z...........z..........z..........z...........z...........z..........z..........z

...........+..................................................................................................+.........

.....2..........2.........2.........2............4..........2..........2..........2..........2.........2.........2..........2
+ ----- + ----- + ----- + ----- + ----- + ----- + ----- + ----- + ----- + ----- + ----- + -----
...9975.....9977....9979....9981....9983....9985....9987....9989....9991....9993....9995....9997
..z............z...........z.........z..........z..........z...........z..........z...........z...........z..........z..........z

10
+ ----- ......................................................................................(3).
9999
z


Step (2): We compute Oddcomp2(z) by equation (4) using i = 1..40. The expanded series will be compared term by term with those in Oddcomp1(z) in order to detect the first occurrence of a missed term in the former.

Oddcomp2(z):=sort(series(sum(1/(z^(2*i+1)*(z^(2*(2*i+1))-1)),i=1..40),z=infinity,10000));

..................................................(4).

..............................1............1.......2......2.......1.......2.......2.......2........2.......4.......1......2......2
Oddcomp(z) := O(------) + ---- + --- + --- + --- + --- + --- + --- + --- + --- + --- + --- + ---
..............................10001......9.....15.....21.....25.....27.....33.....35.....39.......45.....49.....51...55
.............................z.............z........z.......z.......z........z.......z.......z........z.........z.......z........z......z

...........+.............................................................................+...................

.......3.........1.........1..........1..........5...........3........4..........2..........1...........1..........9..........1
+ ----- + ----- + ----- + ----- + ----- + ----- + ----- + ----- + ----- + ----- + ----- + -----
...6855....6859....6861....6865....6867....6873....6875....6877....6879....6881....6885....6887
..z..........z...........z..........z...........z...........z.........z............z............z..........z..........z..........z

..............1...........1.........3...........5..........1..........5........1..........5.........1.........3.........3...........2
+???+ ----- + ----- + ----- + ----- + ----- + ----- + ----- + ----- + ----- + ----- + ----- + -----
.............6891...6893....6895....6897...6901...6903...6905.....6909...6913....6915...6919...6921
............z.........z...........z..........z..........z..........z..........z..........z..........z..........z..........z..........z

.................+..............................................................................+.....................

........1..........1..........1.......1..........1..........1........1...........4
+ ----- + ----- + ----- + ----- + ----- + ----- + ----- + ----- ........................................(5).
.....9983....9985....9987....9989....9993....9995....9997....9999
.....z..........z..........z..........z..........z...........z..........z..........z

The first missing term in Oddcomp2(z) occurs at 6889. The throwing power is computed as follows:

Throwing Power of Oddcomp2(z) := 6889/40 = 172. ....................................(6).

Since throwing power of Comp(z) = 2, the throwing power of Oddcomp(z) is at least 85 times better relative to the former.


3. Conclusions


Throwing power of Oddcomp(z) = 6889/40 = 172 is far superior to that of Comp(z) with a throwing power of 2 only. Even beyond the first miss at 6889, the composite sequence only shows a few sporadic misses indicating that failure is gradual. It is too resource intensive to carry out expansions with i up to several millions but the author conjectures that most probably the throwing power will not diminish but may even increase due to the fact that at the high range the number of odd composites will actually increase relative to the primes for a fixed interval. This might throw some light on why the author failed to detect false reports or counter-examples by Maple's primality tests at high integer ranges [5]. It might just be possible that the chance of catching a counter-example at very high integer range is practically nil and that such counter-examples might be found at the lower range or not at all. Unfortunately there is no absolute proof of the accuracy of primality tests. The author suggests that a better understanding of the properties of Oddcomp(z) might be fruitful in the search for deterministic primality tests. In sequence algebra, we have gained a fair understanding why it is so easy to derive global formulae for composite number sequences such as Comp(z) and Oddcomp(z) and somewhat more difficult for Prime(z). numbers.

4. Reference:

Comments: Not all references given here are directly relevant to the paper but these are included to help readers who might not be familiar with sequence algebra.

1. Huen Y.K.: A Simple Introduction To Sequence Algebra, URL site: http://web.singnet.com.sg/~huens/

2. Huen Y.K.: Unsolved Problems In Sequence Algebra, URL site: http://web.singnet.com.sg /~huens/ .

3. Huen Y.K. : Methods Of Developing Sequence Algebraic Formulations For Comp(z) and Prime(z). URL site: http://web.singnet.com.sg /~huens/ .

4. Huen Y.K.: Improved Formulations For Comp(z) and Prime(z). URL site: http://web.singnet.com.sg/~huens/ .

5. Huen Y.K.: Detecting False Reports In Primality Tests By The Oddcomp(z) Method, URL site: http://web.singnet.com.sg/~huens/ .

6. Huen Y.K. : Lemmata, Corollaries, And Theorems In Sequence Order Analysis. URL site: http://web.singnet.com.sg/~huens/ .

7. Huen Y.K.: A Matrix Map for Prime and Non-prime Numbers, INT. J. Math. Educ. Sci. Technol., 1994, VOL. 25, NO.6, pp 913-920.

8. Huen Y.K.: Some Interesing Properties Of The Natural Number System, Int. J. Math. Educ. Sci. Technol., 1996, VOL.27, NO. 5, 685-691.

9. Huen Y.K.: Visual algebra and its applications, INT. J. Math. Educ. Sci. Technol.,1997, VOL.28 NO.3, 333-344.

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