A139586 Non-Fibonacci numbers with Fibonacci number of divisors.

4, 7, 9, 11, 16, 17, 19, 23, 24, 25, 29, 30, 31, 37, 40, 41, 42, 43, 47, 49, 53, 54, 56, 59, 61, 66, 67, 70, 71, 73, 78, 79, 81, 83, 88, 97, 101, 102, 103, 104, 105, 107, 109, 110, 113, 114, 121, 127, 128, 130, 131, 135, 136, 137, 138

Offset

1,1

Comments

A000005(a(n)) is a Fibonacci number.

Links

Table of n, a(n) for n=1..55.

Example

16 is a term because it is not a Fibonacci number and its number of divisors is 5, a Fibonacci number.

Mathematica

fibs=Fibonacci[Range[15]]; nonfibs=Complement[Range[fibs[[-1]]], fibs]; Select[nonfibs, MemberQ[fibs, DivisorSigma[0, #]]&] (* Harvey P. Dale, Jan 11 2011 *)
With[{fibs=Fibonacci[Range[20]]}, Select[Range[200], !MemberQ[fibs, #]&&MemberQ[fibs, DivisorSigma[0, #]]&]] (* Harvey P. Dale, Apr 04 2026 *)

Crossrefs

Non-Fibonacci numbers: A001690.

Cf. A000005, A000045, A139095, A139587, A139588, A139589, A139590.

Sequence in context: A380834 A310948 A310949 * A310950 A256823 A074341

Adjacent sequences: A139583 A139584 A139585 * A139587 A139588 A139589

Keyword

easy,nonn

Author

Omar E. Pol, May 22 2008

Status

approved