A054012 - OEIS

%I #9 Oct 27 2023 22:00:46

%S 2,1,1,2,2,3,1,3,1,2,3,2,2,1,2,4,2,5,4,1,3,1,2,5,1,1,5,2,3,4,2,3,3,6,

%T 2,1,2,1,8,1,1,7,1,2,4,2,1,2,1,2,8,3,4,4,4,6,1,9,5,4,2,1,1,2,1,2,1,2,

%U 4,2,5,2,4,1,2,2,3,5,8,1,2,4,1,2,2,3,7,5,3,2,2,2,6,2,4,4,1,3,1,2,1,2,6,5,1

%N Nonzero values of n read modulo (number of proper divisors of n).

%F a(n) = A054011(A054009(n)).

%p with(numtheory):

%p [seq(`if`(i mod (tau(i)-1) <> 0,i mod (tau(i)-1),print( )), i=2..220)];

%t Cases[Table[Mod[n,DivisorSigma[0,n]-1],{n,2,200}],Except[0]] (* _Harvey P. Dale_, Nov 12 2011 *)

%Y Cf. A000005, A032741, A054009, A054011.

%K nonn

%O 1,1

%A _Asher Auel_, Jan 17 2000