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A242830 For p = prime(n), a(n) = number of bases 1 < b < p such that b^(p-1) == 1 (mod p^2). 12
0, 0, 0, 0, 2, 0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 0, 1, 0, 0, 2, 0, 1, 0, 0, 1, 0, 1, 0, 1, 1, 2, 2, 1, 0, 0, 1, 0, 2, 0, 0, 0, 1, 1, 0, 1, 1, 2, 1, 0, 2, 1, 0, 1, 0, 1, 1, 3, 0, 0, 1, 1, 1, 1, 0, 2, 0, 3, 0, 2, 2, 2, 2, 2, 1, 1, 0, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 0, 1, 2, 0, 0, 4, 0, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,5

COMMENTS

a(n) > 0 if and only if p is in A134307.

LINKS

Robert Israel, Table of n, a(n) for n = 1..10000

MAPLE

A242830:= proc(n) local p;

  p:= ithprime(n);

  numboccur(1, [seq(b &^ (p-1) mod p^2, b=2..p-1)]);

end proc;

seq(A242830(n), n=1..1000); # Robert Israel, Jul 16 2014

PROG

(PARI) i=0; forprime(p=2, 10^3, a=2; while(a<p, if(Mod(a, p^2)^(p-1)==1, i++); a++); print1(i, ", "); i=0)

CROSSREFS

Cf. A001220, A039678, A134307, A185103, A244249.

Sequence in context: A033770 A216283 A262900 * A101668 A141846 A188171

Adjacent sequences:  A242827 A242828 A242829 * A242831 A242832 A242833

KEYWORD

nonn

AUTHOR

Felix Fröhlich, Jul 12 2014

STATUS

approved

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Last modified August 3 13:49 EDT 2020. Contains 336198 sequences. (Running on oeis4.)