A173207 Cubefree Fibonacci numbers which are not squarefree.

75025, 12586269025, 225851433717, 2111485077978050, 4660046610375530309, 354224848179261915075, 43566776258854844738105, 114059301025943970552219, 42230279526998466217810220532898, 1672445759041379840132227567949787325

Offset: 1

Author

Vladimir Joseph Stephan Orlovsky, Feb 12 2010

Keywords

• nonn

Comments

Subsequence of A061899. [R. J. Mathar, Feb 16 2010]

Apparently contains Fibonacci(25*m), m>0. - Ralf Stephan, Jan 26 2014

Links

• Chai Wah Wu, Table of n, a(n) for n = 1..21

Programs

Mathematica

f[n_]:=Union[Last/@FactorInteger[n]][[ -1]];lst={};Do[fibo=Fibonacci[n];If[f[fibo]==2,AppendTo[lst,fibo]],{n,3,2*5!}];lst
Select[Fibonacci[Range[200]],!SquareFreeQ[#]&&Max[FactorInteger[#][[;;,2]]]<3&] (* Harvey P. Dale, Nov 24 2024 *)

Python

from sympy import factorint
A173207_list = []
a, b = 1, 2
for _ in range(10**2):
    if max(factorint(b).values()) == 2:
        A173207_list.append(b)
    a, b = b, a + b # Chai Wah Wu, Jun 08 2015

Formula

A000045 INTERSECT A067259.

Extensions

Converted cross-references to a formula - R. J. Mathar, Feb 16 2010