A160685 Numbers k >= 1 such that A000005(A000045(k))/A000005(k) is an integer.

1, 3, 5, 6, 7, 8, 10, 11, 13, 14, 15, 17, 19, 21, 22, 23, 24, 25, 26, 27, 29, 30, 31, 33, 34, 35, 37, 38, 39, 40, 41, 42, 43, 46, 47, 50, 51, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 65, 66, 67, 69, 70, 71, 72, 73, 74, 75, 77, 78, 79, 82, 83, 84, 85, 86, 87, 88, 89, 91, 93, 94

Offset: 1

Author

Ctibor O. Zizka, May 23 2009

Keywords

• easy
• nonn

Comments

A080651 is a subsequence. - R. J. Mathar, May 25 2009

Links

• Robert Israel, Table of n, a(n) for n = 1..1073

Crossrefs

Cf. A000045, A000005.

Programs

Maple

A000045 := proc(n) combinat[fibonacci](n) ; end: A000005 := proc(n) numtheory[tau](n) ; end: A063375 := proc(n) A000005(A000045(n)) ; end: for n from 1 to 130 do if A063375(n) mod A000005(n) = 0 then printf("%d,",n) ; fi; od: # R. J. Mathar, May 25 2009

Mathematica

okQ[n_] := With[{tau = DivisorSigma[0, #]&},
  IntegerQ[tau[Fibonacci[n]]/tau[n]]];
Select[Range[100], okQ] (* Jean-François Alcover, May 17 2023 *)

Formula

{n: A000005(n) | A063375(n)}. - R. J. Mathar, May 25 2009

Extensions

2, 12 removed and sequence extended by R. J. Mathar, May 25 2009