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%I #6 Dec 12 2020 06:16:49
%S 449,557,593,649,701,757,793,901,1349,1457,1493,1549,1601,1657,1693,
%T 1801,2249,2357,2393,2449,2501,2557,2593,2701,3149,3257,3293,3349,
%U 3401,3457,3493,3601,4049,4157,4193,4249,4301,4357,4393,4501,4949,5057,5093,5149,5201
%N Numbers b > 1 such that the smallest three primes, i.e., 2, 3 and 5 are base-b Wieferich primes.
%t Select[Range[2, 5250], Function[b, AllTrue[{2, 3, 5}, PowerMod[b, (# - 1), #^2] == 1 &]]] (* _Michael De Vlieger_, Dec 10 2020 *)
%o (PARI) is(n) = forprime(p=1, 5, if(Mod(n, p^2)^(p-1)!=1, return(0))); 1
%Y Cf. A256236. Row 1 of A319060.
%Y 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).
%K nonn
%O 1,1
%A _Felix Fröhlich_, Dec 08 2020
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