FORTRAN source program calculating the Goldbach-Xu’s
numbers with recursive method
Wan-Dong Xu
School of Science, Tianjin University, Tianjin 300072, China
E-mail :
xwandong@sohu.com
Abstract: In this paper we have presented two source programs with FORTRAN 90 language to calculate the
distribution of prime numbers in the sequence of odd numbers and the Goldbach-Xu’s numbers for every even
number respectively. Form the result we can know that this number is oscillatingly increased as an even number
increases.
Keywords: Goldbach’s conjecture; prime; distribution of primes; Goldbach-Xu’s number
MSC: 11P32; 11A41; 11N05; 11N35
1. Introduction
Chinese famous mathematician Luo-Geng Hua had presented in 1979 a route to analyzingly
deduce the solution numbers of Goldbach’s problem for every even number, r(N), through solving
a indefinite equation, ax+by=N, here N is an even, a>0, b>0, and (a, b)=1 [1]. He was failed. After
that time, some researchers devoted themselves in this route, and were also not succeeded [2].
Recently, we have advanced a recursive method to calculate the number of rest sum formulae of
two unequal odd primes, which are to express every even number >6 in natural sequence [3]. Now
we will list some programs of calculating them. By the results of calculating for them, we can
know that the number of rest sum formulae, or say, Goldbach-Xu’s number, is oscillatingly
increased as an even number increases such that the Goldbach’s conjecture is shown to be true.
2. Calculating the distribution of primes in the sequence of odd numbers
We have written a program, named PRIMECAL, with FORTRAN 90 language to calculate
the distribution of odd prime numbers in the sequence of odd numbers in Appendix A. There is a
input number in that program is NUPTO, it means to calculate the primes up to NUPTO, and there
is a output file named D0101T1.DAT, in which an odd prime number is denoted by symbol “1”
and an odd composite number by symbol “0”, and in which there are 100 figures in every row to
indicate 100 odd numbers in order. This is completely the same as ref. [4].
In the Table 1 we listed a distribution table for some prime numbers up to 12,600.
3. Calculating the Goldbach-Xu’s numbers
There is a program calculating with a recursive method, named GOXUNUMB in Appendix B,
with FORTRAN 90 language, to calculate the numbers of rest sum formulae of two unequal odd
primes, or say, the Goldbach-Xu’s numbers, for every even number. There is an input file named
D0101T1.DAT, which is the output file in the section 2 above. And there is an output file named
GOLDXUN1.DAT, which could be opened by the write-board in Windows XP. If one is first run
this program the “status” in program should be set “new”, after then, the “status” should be reset
“old”. In that program most of variant names are the same as symbols in ref. [3].
In the Table 2 we listed some Goldbach-Xu’s numbers for every even numbers starting at 8 and
ending up to 3366. And we can know that the Goldbach-Xu’s number is oscillatingly increased as
an even number increases such that the Goldbach’s conjecture can be verified to be true.
There are two source programs in the author’s hands, which could be sent readers if they need
them and connect to the author.
1
http://www.paper.edu.cn