OFFSET
1,3
COMMENTS
Since 78557 is a Sierpinski number, a(31513) = 0. Are there any values of n so that a(n) = 0 and c(n) is not a Sierpinski number?
MATHEMATICA
lst = {}; Do[If[! PrimeQ[c] && ! PrimeQ@Sqrt[c], k = 1; While[True, p = c*2^k + 1; If[PrimeQ[p] && ! Divisible[MultiplicativeOrder[2, p], c], AppendTo[lst, k]; Break[]]; k++]], {c, 3, 185, 2}]; lst
CROSSREFS
KEYWORD
hard,more,nonn
AUTHOR
Arkadiusz Wesolowski, Jun 13 2013
EXTENSIONS
a(47)-a(56) from Arkadiusz Wesolowski, Jun 16 2013
STATUS
approved