OFFSET
1,2
LINKS
Robert Price, Table of n, a(n) for n = 1..2236
MATHEMATICA
Join[{1}, Select[Range[3000000], PowerMod[13, #^2, #^3] == 1 &]] (* Robert Price, Mar 31 2020 *)
CROSSREFS
Cf. A128393 (k^2 divides 13^k-1).
KEYWORD
nonn
AUTHOR
Alexander Adamchuk, May 14 2010
STATUS
approved