25339Re: Yet another factoring puzzle
- Aug 24, 2013--- In email@example.com, "Kevin Acres" <research@...> wrote:
> > Definition: Let F(n) = ((5^n-9)/4)^2-5 for integer n > 0.What is needed is a formula: F(n)=L(n)*M(n). Then it suffices
> > Exercise 2: For odd n > 1, prove that F(n)/4 is composite.
> I did work out an algorithm to derive one divisor of F(n)/4 for odd n, but
> that's probably a long way from proving it composite.
to show that each of L(n) and M(n) has an odd prime divisor
for odd n > 1. Here is a clue:
4*F(11) = 24414063^2 - 15625^2
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