A325885 - OEIS

%I #4 May 26 2019 15:01:17

%S 10768,24599,27557,29957,33301,35397,45009,49085,55241,60661,63290,

%T 69389,89101,90607,93657,101305,103751,105657,117618,120473,123824,

%U 126449,129473,132857,133524,133948,138149,138896,143882,147717,150793,152985,159317,168920

%N Bases b where exactly nine primes p with p < b exist such that p is a base-b Wieferich prime.

%C Numbers n such that A255920(n) = 9.

%o (PARI) is(n) = my(i=0); forprime(p=1, n-1, if(Mod(n, p^2)^(p-1)==1, i++)); i==9

%Y Cf. A255920.

%Y Cf. bases b with exactly k base-b Wieferich primes less than b: A255921 (k=0), A255922 (k=1), A255923 (k=2), A255924 (k=3), A255925 (k=4), A325881 (k=5), A325882 (k=6), A325883 (k=7), A325884 (k=8), A325886 (k=10).

%K nonn

%O 1,1

%A _Felix Fröhlich_, May 26 2019