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A339532 Numbers b > 1 such that the smallest three primes, i.e., 2, 3 and 5 are base-b Wieferich primes. 6
449, 557, 593, 649, 701, 757, 793, 901, 1349, 1457, 1493, 1549, 1601, 1657, 1693, 1801, 2249, 2357, 2393, 2449, 2501, 2557, 2593, 2701, 3149, 3257, 3293, 3349, 3401, 3457, 3493, 3601, 4049, 4157, 4193, 4249, 4301, 4357, 4393, 4501, 4949, 5057, 5093, 5149, 5201 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..45.

MATHEMATICA

Select[Range[2, 5250], Function[b, AllTrue[{2, 3, 5}, PowerMod[b, (# - 1), #^2] == 1 &]]] (* Michael De Vlieger, Dec 10 2020 *)

PROG

(PARI) is(n) = forprime(p=1, 5, if(Mod(n, p^2)^(p-1)!=1, return(0))); 1

CROSSREFS

Cf. A256236. Row 1 of A319060.

Cf. smallest k primes are base-b Wieferich primes: A339531 (k=2), A339533 (k=4), A339534 (k=5), A339535 (k=6), A339536 (k=7), A339537 (k=8).

Sequence in context: A020466 A142420 A319060 * A105376 A325083 A243402

Adjacent sequences:  A339529 A339530 A339531 * A339533 A339534 A339535

KEYWORD

nonn

AUTHOR

Felix Fröhlich, Dec 08 2020

STATUS

approved

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Last modified November 26 21:07 EST 2021. Contains 349344 sequences. (Running on oeis4.)