cp's OEIS Frontend

A058062 Number of distinct prime factors of sigma(n), the sum of the divisors of n.

%I A058062 #14 Jul 22 2022 23:21:52
%S A058062 0,1,1,1,2,2,1,2,1,2,2,2,2,2,2,1,2,2,2,3,1,2,2,3,1,3,2,2,3,2,1,2,2,2,
%T A058062 2,2,2,3,2,3,3,2,2,3,3,2,2,2,2,2,2,2,2,3,2,3,2,3,3,3,2,2,2,1,3,2,2,3,
%U A058062 2,2,2,3,2,3,2,3,2,3,2,3,1,3,3,2,2,3,3,3,3,3,2,3,1,2,3,3,2,2,3,2,3,2,2,4,2
%N A058062 Number of distinct prime factors of sigma(n), the sum of the divisors of n.
%H A058062 G. C. Greubel, <a href="/A058062/b058062.txt">Table of n, a(n) for n = 1..5001</a>
%F A058062 a(n) = A001221(A000203(n)).
%e A058062 n=81, sigma(81) = 81+27+9+3+1 = 121 = 11^2, so a(81) = 1.
%t A058062 Table[PrimeNu[DivisorSigma[1, n]], {n, 50}] (* _G. C. Greubel_, May 20 2017 *)
%o A058062 (PARI) for(n=1,50, print1(omega(sigma(n)), ", ")) \\ _G. C. Greubel_, May 20 2017
%Y A058062 Cf. A001221, A000203.
%K A058062 nonn
%O A058062 1,5
%A A058062 _Labos Elemer_, Nov 23 2000
%E A058062 Offset corrected by _Sean A. Irvine_, Jul 22 2022