A139587 Non-Fibonacci numbers with non-Fibonacci number of divisors.

6, 10, 12, 14, 15, 18, 20, 22, 26, 27, 28, 32, 33, 35, 36, 38, 39, 44, 45, 46, 48, 50, 51, 52, 57, 58, 60, 62, 63, 64, 65, 68, 69, 72, 74, 75, 76, 77, 80, 82, 84, 85, 86, 87, 90, 91, 92, 93, 94, 95, 96, 98, 99, 100, 106, 108, 111

Offset: 1

Author

Omar E. Pol, May 22 2008

Keywords

• easy
• nonn

Comments

A000005(a(n)) is not a Fibonacci number.

Examples

			6 belongs to the sequence because it is not a Fibonacci number and its number of divisors, 4, is also not a Fibonacci number.
		

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000

Crossrefs

Non-Fibonacci number: A001690. Cf. A000005, A000045, A139095, A139586, A139588, A139589, A139590.

Programs

Mathematica

With[{fibs=Fibonacci[Range[12]]},Select[Range[Max[fibs]],FreeQ[fibs,#] && FreeQ[fibs,DivisorSigma[0,#]]&]] (* Harvey P. Dale, Jun 20 2021 *)

Extensions

Example clarified by Harvey P. Dale, Jun 20 2021