A335976 - OEIS

%I #31 May 27 2024 23:01:20

%S 0,11,13,17,29,31,41,43,47,53,61,71,73,79,81,83,89,97,101,103,107,113,

%T 121,131,137,139,141,149,151,157,167,173,191,193,199,223,229,233,239,

%U 241,243,257,263,271,281,283,293,311,313,317,321,331,339,347,349,353,373,389,397,401,419,421,431,433,443,449,457,461,479,487,509,521,541,557,573,577,587,599,613,617,619,631,641,643,653,661,673,733,739

%N Numbers k such that Fibonacci(6*k) is not a totient.

%C Conjecture: Sequence contains infinitely many primes.

%e 11 is a term since Fibonacci(66) = 27777890035288 is not a totient number.

%o (PARI) isok(n) = !istotient(fibonacci(6*n))

%Y Cf. A000010, A007617, A134492, A280592, A280681.

%K nonn

%O 1,2

%A _Altug Alkan_, Jul 03 2020

%E a(12)-a(20) from _Max Alekseyev_, Aug 02 2020

%E Terms a(21) onward from _Max Alekseyev_, May 19 2024