A159234 Composite numbers n such that 8*n^2-2*n-1 divides the primitive part U(n) of Fibonacci(n).

27, 807, 1707, 2977, 3027, 3277, 4717, 5137, 5677, 5917, 5967, 6187, 7087, 7357, 7597, 7707, 8217, 9117, 9297, 9387, 9667, 9877, 9927, 9997, 10387, 11097, 11647, 11797, 12727, 13407, 13867, 15757, 15987, 16327, 16507, 16857, 17347, 17767, 18237, 18817, 18997

Offset

1,1

Links

Table of n, a(n) for n=1..41.

Chris Caldwell, The Prime Glossary, Fibonacci number

Mathematica

lst = {1}; Do[f = Fibonacci[a]; Do[f = f/GCD[f, lst[[d]]], {d, Most[Divisors[a]]}]; AppendTo[lst, f], {a, 2, 19000}]; Flatten[Table[If[! PrimeQ[n] && Mod[lst[[n]], 8*n^2 - 2*n - 1] == 0, n, {}], {n, 19000}]] (* Arkadiusz Wesolowski, Dec 12 2011 *)

Crossrefs

Subsequence of A159259.

Cf. A000045, A023172, A061446, A159231, A181890.

Sequence in context: A138979 A183505 A218717 * A120715 A065922 A376778

Adjacent sequences: A159231 A159232 A159233 * A159235 A159236 A159237

Keyword

nonn

Author

Arkadiusz Wesolowski, Apr 06 2009

Status

approved