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Partial sums of A046897.
0

%I #22 Jun 21 2024 07:33:37

%S 1,4,8,11,17,29,37,40,53,71,83,95,109,133,157,160,178,217,237,255,287,

%T 323,347,359,390,432,472,496,526,598,630,633,681,735,783,822,860,920,

%U 976,994,1036,1132,1176,1212,1290,1362,1410,1422,1479,1572,1644,1686,1740,1860

%N Partial sums of A046897.

%H Wikipedia, <a href="https://en.wikipedia.org/wiki/Jacobi%27s_four-square_theorem">Jacobi four square theorem</a>

%F G.f.: 1/(1 - q) * Sum_{k>=1} k * q^k / (1 + (-q)^k). - _Seiichi Manyama_, Jun 21 2024

%t Accumulate[DivisorSum[#1, # &, Mod[#, 4] != 0 &] & /@ Range[50]] (* _Jayanta Basu_, Jun 30 2013 *)

%o (PARI) my(N=60, q='q+O('q^N)); Vec(sum(k=1, N, k*q^k/(1+(-q)^k))/(1-q)) \\ _Seiichi Manyama_, Jun 21 2024

%Y Cf. A046897.

%K nonn

%O 1,2

%A _N. J. A. Sloane_

%E Offset changed from 0 to 1 by _Seiichi Manyama_, Jun 21 2024