A238497 Cubefree Fibonacci numbers.

1, 1, 2, 3, 5, 13, 21, 34, 55, 89, 233, 377, 610, 987, 1597, 4181, 6765, 10946, 17711, 28657, 75025, 121393, 196418, 317811, 514229, 1346269, 2178309, 3524578, 5702887, 9227465, 24157817, 39088169, 63245986, 102334155, 165580141, 433494437

Offset: 1

Author

Carmine Suriano, Feb 27 2014

Keywords

• nonn

Examples

			a(21) = 75025 since 75025 = fib(25) = 5^2 * 3001 has no cubic factor.
		

Links

• Carmine Suriano, Table of n, a(n) for n = 1..165

Crossrefs

Cf. A000045, A061305.

Intersection of A004709 and A000045.

Programs

Haskell

a238497 n = a238497_list !! (n-1)
a238497_list = filter ((== 1) . a212793) $ tail a000045_list
-- Reinhard Zumkeller, Feb 28 2014

Mathematica

Select[Fibonacci@ Range@ 120, Max[Last /@ FactorInteger@ #] < 3 &] (* Giovanni Resta, Feb 27 2014 *)

Formula

A010056(a(n)) * A212793(a(n)) = 1. - Reinhard Zumkeller, Feb 28 2014

Extensions

b-file corrected from Giovanni Resta, Feb 28 2014