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

1,3

Links

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

Formula

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

Example

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

Mathematica

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

Prog

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

Crossrefs

Cf. A000045, A061305.

Intersection of A004709 and A000045.

Sequence in context: A145908 A173830 A224223 * A061305 A177374 A142881

Adjacent sequences: A238494 A238495 A238496 * A238498 A238499 A238500

Keyword

nonn

Author

Carmine Suriano, Feb 27 2014

Extensions

b-file corrected from Giovanni Resta, Frb 28 2014

Status

approved