OFFSET
1,2
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..467
MATHEMATICA
Select[Range[0, 120], SquareFreeQ[((4^# - 1) / 3)] &] (* Vincenzo Librandi, Aug 03 2015 *)
PROG
(Magma) [n: n in [1..115] | IsSquarefree((4^n-1) div 3)]; // Vincenzo Librandi, Aug 03 2015
(PARI) isok(k) = issquarefree((4^k-1)/3); \\ Michel Marcus, Feb 25 2021
CROSSREFS
KEYWORD
nonn
AUTHOR
Omar E. Pol, Aug 02 2015
STATUS
approved