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A086156 a(n) = sigma(n^2) - n*sigma(n). 1

%I #13 Dec 15 2023 06:19:25

%S 0,1,1,3,1,19,1,7,4,37,1,67,1,63,43,15,1,145,1,121,69,139,1,211,6,189,

%T 13,199,1,661,1,31,145,313,87,475,1,387,195,337,1,1155,1,427,241,559,

%U 1,691,8,817,319,577,1,1171,163,519,393,877,1,2413,1,999,345,63,213,2599

%N a(n) = sigma(n^2) - n*sigma(n).

%H Michel Marcus, <a href="/A086156/b086156.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n) = A065764(n) - A064987(n). - _Michel Marcus_, Aug 23 2019

%F Sum_{k=1..n} a(k) ~ (5*zeta(3)/Pi^2 - Pi^2/18) * n^3. - _Amiram Eldar_, Dec 15 2023

%t Table[DivisorSigma[1, w*w]-w*DivisorSigma[1, w], {w, 1, 256}]

%o (PARI) a(n) = sigma(n^2) - n*sigma(n); \\ _Michel Marcus_, Aug 23 2019

%Y Cf. A000203, A000593, A046913, A064987, A065764.

%K nonn,easy

%O 1,4

%A _Labos Elemer_, Aug 14 2003

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Last modified March 28 18:04 EDT 2024. Contains 371254 sequences. (Running on oeis4.)