OFFSET
1,1
COMMENTS
a(4) = 9639595369 is from Fischer's tables. No more terms up to 2*10^14.
LINKS
Richard Fischer, Fermatquotienten von 2 bis 1052, Dec 19 2019.
Wikipedia, Wieferich prime
PROG
(PARI) forprime(p=2, 1e8, if(Mod(33, p^2)^(p-1)==1, print1(p", ")))
CROSSREFS
Wieferich primes to base b: A001220 (b=2), A014127 (b=3), A123692 (b=5), A212583 (b=6), A123693 (b=7), A045616 (b=10), A111027 (b=12), A128667 (b=13), A234810 (b=14), A242741 (b=15), A128668 (b=17), A244260 (b=18), A090968 (b=19), A242982 (b=20), A298951 (b=22), A128669 (b=23), A306255 (b=26), A306256 (b=30), A331424 (b=31), this sequence (b=33), A397319 (b=35), A331426 (b=37), A397320 (b=40), A331427 (b=41).
Cf. A039951.
KEYWORD
nonn,hard,more
AUTHOR
Daniel Okwor, Jun 20 2026
STATUS
approved