OFFSET
1,2
COMMENTS
Conjecture: the odd values of ceiling(2^(2^k mod k)/3) are Jacobsthal numbers (and the even values are 1 plus a Jacobsthal number).
MATHEMATICA
Select[Range[493], OddQ[Ceiling[2^PowerMod[2, #, #]/3]]&] (* James C. McMahon, Jun 14 2024 *)
PROG
(PARI) isok(k) = (ceil(2^lift(Mod(2, k)^k)/3) % 2) == 1; \\ Michel Marcus, Jun 14 2024
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Paul Barry, Oct 08 2005
STATUS
approved