OFFSET
0,2
COMMENTS
Searched up to 7742*2^100000 + 1 (3871*2^100001 + 1 is the format in the Yves Gallot's Proth Program)
LINKS
Chris K. Caldwell, The Prime Pages, 3871*2^1925976+1 (7742*2^1925975+1)
Chris K. Caldwell, The Prime Pages, 1925975*2^1989191+1
FORMULA
a(n) = least integer b greater than a(n-1) such that a(n-1)*2^b + 1 is prime
MATHEMATICA
t = {a = 1}; Do[If[PrimeQ[a*2^n + 1], AppendTo[t, a = n]], {n, 2, 2300}]; t (* Jayanta Basu, Jun 29 2013 *)
CROSSREFS
KEYWORD
hard,nonn,more
AUTHOR
Chad Davis (cad16(AT)po.cwru.edu)
EXTENSIONS
a(18) from Kellen Shenton, May 08 2022
a(19) from Kellen Shenton, May 14 2022
STATUS
approved