A130331 Number of divisors of A123240(n).

4, 4, 4, 6, 4, 4, 6, 6, 4, 4, 4, 4, 6, 6, 4, 4, 4, 9, 4, 4, 6, 6, 4, 10, 6, 4, 6, 4, 4, 4, 12, 4, 6, 7, 4, 6, 4, 12, 4, 6, 6, 4, 10, 4, 12, 4, 4, 4, 12, 4, 6, 4, 4, 4, 12, 6, 6, 9, 4, 12, 4, 10, 4, 6, 6, 4, 4, 16, 4, 4, 6, 4, 12, 4, 12, 4, 4, 12, 4, 4, 4, 15, 4, 4, 6, 6, 12, 6, 4, 12, 4, 4, 12, 4, 10, 6, 4

Offset: 1

Author

Giovanni Teofilatto, Aug 07 2007

Keywords

• easy
• nonn

Comments

By definition, each term is in A001690. - R. J. Mathar, Jan 15 2008

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A000005, A000379, A123240.

Programs

Mathematica

seq[max_] := Module[{d = DivisorSigma[0, Range[max]], dmax, k = 2}, dmax = Max[d]; While[Fibonacci[k] < dmax, k++]; Select[d, !MemberQ[Fibonacci[Range[2, k]], #] &]]; seq[300] (* Amiram Eldar, Apr 08 2024 *)

Formula

a(n) = A000005(A123240(n)). - R. J. Mathar, Jan 15 2008

Extensions

More terms from R. J. Mathar, Jan 15 2008