%I #15 May 13 2022 04:55:07
%S 2,3,4,7,9,10,11,12,13,17,19,20,23,24,27,28,29,31,36,37,41,43,47,48,
%T 50,53,59,60,61,63,67,71,72,73,76,79,83,84,89,96,97,99,100,101,103,
%U 107,108,109,110,113,120,127,131,137,139,140,144,149,151,157,161,163,167,168
%N Numbers k such that F(k^2+1) == 1 (mod k) where F(k) denotes the k-th Fibonacci number.
%C Except p=5, all prime numbers p are in the sequence.
%H Amiram Eldar, <a href="/A086391/b086391.txt">Table of n, a(n) for n = 1..1000</a>
%t Select[Range[200], Mod[Fibonacci[#^2 + 1], #] == 1 &] (* _Amiram Eldar_, May 13 2022 *)
%o (PARI) isok(n) = ((fibonacci(n^2+1) % n) == 1); \\ _Michel Marcus_, Dec 06 2013
%Y Cf. A000045, A002522.
%K nonn
%O 1,1
%A _Benoit Cloitre_, Sep 06 2003