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A339534 Numbers b > 1 such that the smallest five primes, i.e., 2, 3, 5, 7 and 11 are base-b Wieferich primes. 6
19601, 22049, 48149, 52057, 67357, 84457, 85193, 93493, 104057, 113257, 115757, 132857, 160849, 171793, 186101, 198449, 206749, 209249, 224549, 228457, 235493, 261593, 265501, 280801, 297901, 317501, 326701, 329201, 329849, 346301, 359857, 374293, 374849 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..33.

MATHEMATICA

Select[Range[2, 375000], Function[b, AllTrue[{2, 3, 5, 7, 11}, PowerMod[b, (# - 1), #^2] == 1 &]]] (* Michael De Vlieger, Dec 10 2020 *)

PROG

(PARI) is(n) = forprime(p=1, 11, if(Mod(n, p^2)^(p-1)!=1, return(0))); 1

CROSSREFS

Cf. A256236. Row 1 of A319062.

Cf. smallest k primes are base-b Wieferich primes: A339531 (k=2), A339532 (k=3), A339533 (k=4), A339535 (k=6), A339536 (k=7), A339537 (k=8).

Sequence in context: A022213 A093219 A184493 * A319062 A344829 A221333

Adjacent sequences:  A339531 A339532 A339533 * A339535 A339536 A339537

KEYWORD

nonn

AUTHOR

Felix Fröhlich, Dec 08 2020

STATUS

approved

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Last modified June 15 18:19 EDT 2021. Contains 345049 sequences. (Running on oeis4.)