OFFSET
1,1
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..169 (terms below 10^11; terms 1..87 from Robert G. Wilson v)
Eric Weisstein's World of Mathematics, Fermat Pseudoprime.
MATHEMATICA
Do[ f=PowerMod[ 31, 2n-1, 2n ]; If[ f==1, Print[ 2n ] ], {n, 2, 500000} ]
lst = {}; Do[ If[ PowerMod[31, 2n - 1, 2n] == 1, AppendTo[lst, 2n]], {n, 2, 2^31}]; lst (* Robert G. Wilson v, Jun 01 2007 *)
PROG
(PARI) is(k) = k > 2 && !(k % 2) && Mod(31, k)^(k-1) == 1; \\ Amiram Eldar, Sep 29 2024
CROSSREFS
KEYWORD
nonn
AUTHOR
Alexander Adamchuk, May 26 2007
EXTENSIONS
More terms from Robert G. Wilson v, Jun 01 2007
STATUS
approved