%I A071774
%S A071774 3,7,13,17,23,37,43,53,67,73,83,97,103,127,137,157,163,167,173,193,197,
%T A071774 223,227,257,277,283,293,313,317,337,367,373,383,397,433,443,457,463,
%U A071774 467,487,503,523,547,577,587,593,607,613,617,643,647,653,673,683,727
%N A071774 Related to Pisano periods: n such that the period of Fibonacci numbers 
               mod n equals 2*(n+1).
%C A071774 Terms are primes with final digit 3 or 7.
%o A071774 (PARI) for(n=2,5000,t=2*(n+1);good=1;if(fibonacci(t)%n==0, for(s=0,t,
               if(fibonacci(t+s)%n!=fibonacci(s)%n,good=0;break); if(s>1&&s<t-1&&fibonacci(s)%n==0,
               cur=s;good2=1;for(ss=0,s, if(fibonacci(ss+s)%n!=fibonacci(ss)%n,good2=0;
               break)); if(good2,good=0;break););); if(good,print1(n,",")))) (Klasen)
%Y A071774 Cf. A001175, A060305, A071776.
%Y A071774 Sequence in context: A034913 A040148 A097957 this_sequence A019403 A045422 
               A113003
%Y A071774 Adjacent sequences: A071771 A071772 A071773 this_sequence A071775 A071776 
               A071777
%K A071774 easy,nonn
%O A071774 1,1
%A A071774 Benoit Cloitre (benoit7848c(AT)orange.fr), Jun 04 2002
%E A071774 More terms from Lambert Klasen (Lambert.Klasen(AT)gmx.net), Dec 21 2004