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%I #14 Mar 30 2012 17:26:37
%S 0,1,1,3,1,7,1,7,4,1,1,11,1,15,19,15,1,28,1,37,5,31,1,31,6,21,13,31,1,
%T 13,1,31,1,43,39,20,1,27,27,67,1,3,1,7,7,55,1,71,8,73,31,87,1,91,19,
%U 39,73,67,1,61,1,39,33,63,45,7,1,67,85,129,1,157,1,45,109,51,93,21,1,31,40,91,1,123,13,51,43,151,1,49,15,7,109,103,51,151,1,113,25,124,1,73,1,141,123,115,1,3,1,133,51,111,1,111,7,121,121
%N sigma(n^2) modulo sigma(n).
%C a(n)=1 iff n is prime. Apparently a(n)>2 for composite n's.
%F a(n) = A065764(n) mod A000203(n).
%t Table[Mod[DivisorSigma[1,n^2],DivisorSigma[1,n]],{n,200000}]
%Y Cf. A000203.
%K nonn,easy
%O 1,4
%A _Zak Seidov_, Mar 06 2011