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A248865 Primes p that set a new record for the number of bases 1 < b < p for which p is a base-b Wieferich prime. 4

%I

%S 2,11,269,487,653,1093,3511,1006003

%N Primes p that set a new record for the number of bases 1 < b < p for which p is a base-b Wieferich prime.

%C Primes p where A242830(i) reaches record values, where i is the index of p in A000040.

%C The corresponding number of bases are 0, 2, 3, 4, 5, 10, 11, 12. - _Jianing Song_, Feb 07 2019

%o (PARI) my(r=-1); forprime(p=2, , my(b=2, i=0); while(b < p, if(Mod(b, p^2)^(p-1)==1, i++); b++); if(i > r, print1(p, ", "); r=i)) \\ changed to include a(1) = 2 by _Jianing Song_, Feb 07 2019

%Y Cf. A000040, A175932, A242830.

%Y Subsequence of A175932. Apart from the first term, subsequence of A134307.

%K nonn,hard,more

%O 1,1

%A _Felix Fröhlich_, Mar 07 2015

%E a(1) = 2 inserted by _Jianing Song_, Feb 07 2019

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Last modified August 8 14:04 EDT 2020. Contains 336298 sequences. (Running on oeis4.)