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A229342 a(n) = sigma(n'), the sum of divisors of the arithmetic derivative of n.

%I A229342 #31 Feb 25 2018 09:54:23
%S A229342 1,1,7,1,6,1,28,12,8,1,31,1,13,15,63,1,32,1,60,18,14,1,84,18,24,40,63,
%T A229342 1,32,1,186,24,20,28,168,1,32,31,126,1,42,1,124,56,31,1,248,24,78,42,
%U A229342 120,1,121,31,168,36,32,1,168,1,48,72,508,39,62,1,195,42
%N A229342 a(n) = sigma(n'), the sum of divisors of the arithmetic derivative of n.
%C A229342 a(1) is undefined.
%H A229342 Antti Karttunen, <a href="/A229342/b229342.txt">Table of n, a(n) for n = 2..20000</a>
%F A229342 a(n) = A000203(A003415(n)).
%e A229342 For n=4, sigma(n') = sigma(4') = sigma(4) = 7.
%e A229342 For n=7, sigma(n') = sigma(7') = sigma(1) = 1.
%o A229342 (PARI) rd(n) = {local(fac); if(n<1, 0, fac=factor(n); sum(i=1, matsize(fac)[1], n*fac[i, 2]/fac[i, 1];));} \\ from A003415
%o A229342 a(n) = sigma(rd(n)); \\ _Michel Marcus_, Sep 24 2013
%Y A229342 Cf. A000203, A003415.
%Y A229342 Cf. also A229340, A229341, A229343, A229344.
%K A229342 nonn
%O A229342 2,3
%A A229342 _Luca Brigada Villa_, Sep 24 2013