A339533 Numbers b > 1 such that the smallest four primes, i.e., 2, 3, 5 and 7 are base-b Wieferich primes.

557, 901, 1549, 2449, 4049, 5293, 5849, 6193, 7057, 7957, 8801, 9701, 12349, 13249, 14093, 14993, 15857, 16201, 16757, 18001, 19601, 20501, 21149, 21493, 22049, 23257, 23293, 24893, 25057, 25793, 26657, 27557, 28549, 30349, 31949, 32849, 33301, 34201, 35801

Offset

1,1

Links

Table of n, a(n) for n=1..39.

Mathematica

Select[Range[2, 36000], Function[b, AllTrue[{2, 3, 5, 7}, PowerMod[b, (# - 1), #^2] == 1 &]]] (* Michael De Vlieger, Dec 10 2020 *)

Prog

(PARI) is(n) = forprime(p=1, 7, if(Mod(n, p^2)^(p-1)!=1, return(0))); 1

Crossrefs

Cf. A256236. Row 1 of A319061.

Cf. smallest k primes are base-b Wieferich primes: A339531 (k=2), A339532 (k=3), A339534 (k=5), A339535 (k=6), A339536 (k=7), A339537 (k=8).

Sequence in context: A177331 A289564 A319061 * A344828 A260066 A105979

Adjacent sequences: A339530 A339531 A339532 * A339534 A339535 A339536

Keyword

nonn

Author

Felix Fröhlich, Dec 08 2020

Status

approved