OFFSET
1,2
COMMENTS
No other terms below 10^15.
MATHEMATICA
Join[{1, 5}, Select[Range[4000000], PowerMod[13, #, #] == 8 &]] (* Robert Price, Apr 10 2020 *)
CROSSREFS
KEYWORD
nonn,hard,more
AUTHOR
Max Alekseyev, Nov 23 2017
STATUS
approved