OFFSET
1,2
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..3000 (terms 1..56 from R. J. Mathar)
MATHEMATICA
Select[Range[20000], IntegerQ[(PowerMod[9, #, #^2 ]-1)/#^2 ]&]
PROG
(PARI) is(k) = Mod(9, k^2)^k == 1; \\ Amiram Eldar, May 21 2024
CROSSREFS
KEYWORD
nonn
AUTHOR
Alexander Adamchuk, Jan 05 2007
STATUS
approved