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A244796 Number of moduli m such that (prime(n) mod m) = 1.

%I A244796 #10 Jul 05 2017 02:57:35
%S A244796 0,1,2,3,3,5,4,5,3,5,7,8,7,7,3,5,3,11,7,7,11,7,3,7,11,8,7,3,11,9,11,7,
%T A244796 7,7,5,11,11,9,3,5,3,17,7,13,8,11,15,7,3,11,7,7,19,7,8,3,5,15,11,15,7,
%U A244796 5,11,7,15,5,15,19,3,11,11,3,7,11,15,3,5,17
%N A244796 Number of moduli m such that (prime(n) mod m) = 1.
%C A244796 Except for the initial 0, this is column 1 of the array at A244740,
%H A244796 Clark Kimberling, <a href="/A244796/b244796.txt">Table of n, a(n) for n = 1..1000</a>
%F A244796 a(n) = A000005(prime(n) - 1) - 1. - _Gionata Neri_, Jul 04 2017
%e A244796 prime(5) = 11 = (1 mod m) for m = 2, 5, 10, so that a(5) = 3.
%t A244796 z = 300; f[n_, m_] := If[Mod[Prime[n], m] == 1, 1, 0];
%t A244796 t = Table[f[n, m], {n, 1, z}, {m, 1, Prime[n]}];
%t A244796 Table[Count[t[[k]], 1], {k, 1, z}] (* A244796 *)
%Y A244796 Cf. A244740, A244797, A244798.
%K A244796 nonn,easy
%O A244796 1,3
%A A244796 _Clark Kimberling_, Jul 06 2014