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%I #20 May 19 2022 12:08:41
%S 17,65,145,485,649,1297,577,2024,5185,8182,7057,8749,14401,30753,
%T 56449,57601,77401,129473,51841,129601,254017,296449,202501,389377
%N Smallest base b such that there exist exactly n Wieferich pseudoprimes (composites c satisfying b^(c-1) == 1 (mod c^2)) less than b.
%o (PARI) for(n=1, 10, b=2; while(b > 0, i=0; forcomposite(c=2, b, if(Mod(b, c^2)^(c-1)==1, i++)); if(i==n, print1(b, ", "); break({1})); b++))
%o (Python)
%o from itertools import count
%o from sympy import isprime
%o def A255885(n):
%o for b in count(1):
%o if n == sum(1 for c in range(2,b+1) if not isprime(c) and pow(b,c-1,c**2) == 1):
%o return b # _Chai Wah Wu_, May 18 2022
%Y Cf. A244752, A252232, A255901.
%K nonn,more
%O 1,1
%A _Felix Fröhlich_, Mar 09 2015
%E a(20) from _Chai Wah Wu_, May 18 2022
%E a(21)-a(24) from _Chai Wah Wu_, May 19 2022
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