OFFSET
1,2
COMMENTS
Subset of A067946 (numbers n such that n divides 5^n-1).
LINKS
Robert Israel, Table of n, a(n) for n = 1..1000
Taro Morishima, Über die Fermatsche Vermutung, Proc. Imp. Acad., Volume 4, Number 10 (1928), 590-592.
MAPLE
select(t -> (5 &^t - 1) mod (t^2) = 0, [$1..10^5]); # Robert Israel, Jul 15 2018
MATHEMATICA
Select[Range[30000], IntegerQ[(PowerMod[5, #, #^2 ]-1)/#^2 ]&]
PROG
(PARI) isok(n) = Mod(5, n^2)^n == 1; \\ Michel Marcus, Apr 23 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
Alexander Adamchuk, Jan 05 2007
EXTENSIONS
More terms from Ryan Propper and Alexander Adamchuk, Jan 05 2007
STATUS
approved