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 A386780 #15 Aug 04 2025 06:15:24
%S A386780 0,1,520,19710,266304,1953250,10249200,40353950,136348160,387952659,
%T A386780 1015690000,2357949022,5248851840,10604501570,20984054000,38498557500,
%U A386780 69810262016,118587881410,201735382680,322687704638,520158288000,795376354500,1226133491440,1801152673630
%N A386780 a(n) = n^3*sigma_6(n).
%H A386780 Vincenzo Librandi, <a href="/A386780/b386780.txt">Table of n, a(n) for n = 0..10000</a>
%F A386780 G.f.: Sum_{k>=1} k^9*x^k*(x^(2*k) + 4*x^k + 1)/(1 - x^k)^4.
%F A386780 a(n) = n^3*A013954(n).
%F A386780 Dirichlet g.f.: zeta(s-3)*zeta(s-9). - _R. J. Mathar_, Aug 03 2025
%t A386780 Table[n^3*DivisorSigma[6, n], {n, 0, 30}]
%t A386780 nmax = 30; CoefficientList[Series[Sum[k^9*x^k*(x^(2*k) + 4*x^k + 1)/(1 - x^k)^4, {k, 1, nmax}], {x, 0, nmax}], x]
%o A386780 (Magma) [0] cat [n^3*DivisorSigma(6, n): n in [1..35]]; // _Vincenzo Librandi_, Aug 04 2025
%Y A386780 Cf. A282211, A386746, A282213, A386748, A282781, A386781, A386782.
%Y A386780 Cf. A013954, A386750, A386777.
%K A386780 nonn,mult
%O A386780 0,3
%A A386780 _Vaclav Kotesovec_, Aug 02 2025