cp's OEIS Frontend

A347876 a(n) = A323905(sigma(n)), where A323905(x) = A156552(x) - A048675(x).

%I A347876 #5 Sep 19 2021 22:01:19
%S A347876 0,0,1,0,2,7,4,4,0,8,7,25,8,18,18,0,8,32,13,26,26,21,18,35,0,26,32,60,
%T A347876 14,48,26,26,41,22,41,32,128,35,60,36,26,88,49,63,98,48,41,3073,128,
%U A347876 1024,48,32,22,78,48,78,71,36,35,138,1024,88,228,0,63,103,193,64,88,103,48,100,2048,386,3073,69,88,138,71
%N A347876 a(n) = A323905(sigma(n)), where A323905(x) = A156552(x) - A048675(x).
%H A347876 <a href="/index/Pri#prime_indices">Index entries for sequences computed from indices in prime factorization</a>
%H A347876 <a href="/index/Si#SIGMAN">Index entries for sequences related to sigma(n)</a>
%F A347876 a(n) = A323905(A000203(n)).
%F A347876 a(n) = A332221(n) - A331750(n).
%o A347876 (PARI)
%o A347876 A048675(n) = { my(f = factor(n)); sum(k=1, #f~, f[k, 2]*2^primepi(f[k, 1]))/2; }; \\ From A048675
%o A347876 A156552(n) = {my(f = factor(n), p, p2 = 1, res = 0); for(i = 1, #f~, p = 1 << (primepi(f[i, 1]) - 1); res += (p * p2 * (2^(f[i, 2]) - 1)); p2 <<= f[i, 2]); res}; \\ From A156552
%o A347876 A323905(n) = (A156552(n) - A048675(n));
%o A347876 A347876(n) = A323905(sigma(n));
%Y A347876 Cf. A000203, A048675, A156552, A323905, A331750, A332221, A347875.
%K A347876 nonn
%O A347876 1,5
%A A347876 _Antti Karttunen_, Sep 19 2021