login
Numbers k such that A000045(k) mod 5 is prime.
0

%I #19 Sep 08 2022 08:46:24

%S 3,4,6,7,13,14,16,17,23,24,26,27,33,34,36,37,43,44,46,47,53,54,56,57,

%T 63,64,66,67,73,74,76,77,83,84,86,87,93,94,96,97,103,104,106,107,113,

%U 114,116,117,123,124,126,127,133,134,136,137,143,144,146,147,153,154,156,157

%N Numbers k such that A000045(k) mod 5 is prime.

%C Position of prime numbers in A082116.

%F G.f.: x*(3*x^2+4*x+3)*(x^2-x+1)/((x+1)*(x^2+1)*(x-1)^2). - _Alois P. Heinz_, Jul 08 2019

%t Select[Range[160], MemberQ[{2, 3}, Mod[Fibonacci[#], 5]] &]

%o (Magma) [n: n in [0..200] | IsPrime(Fibonacci(n) mod 5)];

%Y Cf. A000045, A082116.

%Y Partial sums of A010123.

%K nonn,easy

%O 1,1

%A _Vincenzo Librandi_, Jul 06 2019