Never a dull moment around here

[davieddy]

One minute I'm discussing TF to 72,
and the next I am failing to get UncWilly to
grasp that if for some bizarre reason you want
to trawl the exponents <1 Billion for factors,
it would be better to work downwards.

David

[science_man_88]

Originally Posted by davieddy

if for some bizarre reason you want
to trawl the exponents <1 Billion for factors,
it would be better to work downwards.

really, on second thought I don't see it as bizarre because 2*k*p+1 if k= composite such that it breaks into 2 primes r,s smaller than p such that 2*k*p+1 is lower than 2^r-1 or 2^s-1 or both. if k is prime switch p and k you've now got a impossible factor of 2^k-1 if 2*k*p+1 is less than 2^k-1. the bizarre part for me would be the likelihood of such happening.

edit: k could also be composite * prime and be composite.