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%I #12 May 09 2017 00:08:51
%S 0,1,2,3,2,3,2,2,3,3,2,5,2,3,3,4,2,4,3,5,3,3,2,4,4,3,4,5,2,4,3,5,3,3,
%T 3,4,3,3,3,4,3,4,4,5,5,3,3,5,5,5,3,5,3,4,3,4,4,3,4,6,2,4,5,4,3,4,3,5,
%U 3,4,2,5,2,4,6,6,3,4,4,6,4,4,4,6,3,4,3,4,3,6,3,5,4,4,4,7,3,6,5,5,3,4,2,4,4
%N Number of distinct prime factors of Sigma_4[n], the sum of 4th powers of divisors of n.
%H Harry J. Smith, <a href="/A066102/b066102.txt">Table of n, a(n) for n=1..1000</a>
%F a(n) = A001221(DivisorSigma(4, n)) = A001221(A001159(n)).
%t Table[PrimeNu[DivisorSigma[4, n]], {n, 1, 50}] (* _G. C. Greubel_, May 08 2017 *)
%o (PARI) { for (n=1, 1000, a=omega(sigma(n, 4)); write("b066102.txt", n, " ", a) ) } \\ _Harry J. Smith_, Nov 14 2009
%Y Cf. A001159, A001221.
%K nonn
%O 1,3
%A _Labos Elemer_, Dec 04 2001
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