This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A363974 #11 Jun 30 2023 15:36:20 %S A363974 1,1,4,1,7,4,11,1,19,7,22,4,29,11,46,1,46,19,56,7,80,22,79,4,98,29, %T A363974 124,11,121,46,137,1,178,46,188,19,191,56,242,7,232,80,254,22,337,79, %U A363974 301,4,336,98,400,29,379,124,434,11,494,121,466,46,497,137,623,1,596,178,596,46,712,188,667,19 %N A363974 Expansion of Sum_{k>0} x^k / (1 - x^(2*k))^3. %F A363974 G.f.: Sum_{k>0} k*(k+1)/2 * x^(2*k-1) / (1 - x^(2*k-1)). %F A363974 a(n) = Sum_{d|n, d==1 mod 2} binomial((d+1)/2+1,2). %t A363974 a[n_] := DivisorSum[n, Binomial[(#+1)/2+1,2] &, OddQ[#] &]; Array[a, 100] (* _Amiram Eldar_, Jun 30 2023 *) %o A363974 (PARI) a(n) = sumdiv(n, d, (d%2==1)*binomial((d+1)/2+1, 2)); %Y A363974 Cf. A001227, A113415. %Y A363974 Cf. A363969. %K A363974 nonn %O A363974 1,3 %A A363974 _Seiichi Manyama_, Jun 30 2023