A248757 - OEIS

%I #16 May 25 2026 16:08:04

%S 6,10,11,28,149,172,185,754,815,1510,1594,3160,3755,10654,12743,71807,

%T 155957

%N Indices of prime Fibonacci 5-step numbers, A001591.

%C This sequence is similar to A105756 but uses the indexing scheme defined by A001591 whose indices start with 0.

%C a(18) > 2*10^5.

%H Tony D. Noe and Jonathan Vos Post, <a href="http://www.cs.uwaterloo.ca/journals/JIS/VOL8/Noe/noe5.html">Primes in Fibonacci n-step and Lucas n-step Sequences,</a> J. of Integer Sequences, Vol. 8 (2005), Article 05.4.4

%H Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Fibonaccin-StepNumber.html">Fibonacci n-Step Number</a>

%F a(n) = A105756(n) + 3.

%t a = {0, 0, 0, 0, 1}; For[n = 5, n ≤ 1000, n++, sum = Plus @@ a;

%t   If[PrimeQ[sum], Print[n]]; a = RotateLeft[a]; a[[5]] = sum]

%Y Cf. A001591, A105756.

%K nonn,more

%O 1,1

%A _Robert Price_, Oct 13 2014