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 A386784 #18 Aug 04 2025 02:46:51
%S A386784 0,1,272,6642,69888,391250,1806624,5767202,17895424,43584723,
%T A386784 106420000,214373522,464196096,815759282,1568678944,2598682500,
%U A386784 4581294080,6975840962,11855044656,16983693362,27343680000,38305755684,58309597984,78311265122,118861406208,152832421875
%N A386784 a(n) = n^4*sigma_4(n).
%H A386784 Vincenzo Librandi, <a href="/A386784/b386784.txt">Table of n, a(n) for n = 0..10000</a>
%F A386784 G.f.: Sum_{k>=1} k^4*x^k*(1 + 247*x^k + 4293*x^(2*k) + 15619*x^(3*k) + 15619*x^(4*k) + 4293*x^(5*k) + 247*x^(6*k) + x^(7*k))/(1 - x^k)^9.
%F A386784 a(n) = n^4*A001159(n).
%F A386784 Dirichlet g.f.: zeta(s-4)*zeta(s-8). - _R. J. Mathar_, Aug 03 2025
%t A386784 Table[n^4*DivisorSigma[4, n], {n, 0, 40}]
%t A386784 nmax = 40; CoefficientList[Series[Sum[k^4*x^k*(1 + 247*x^k + 4293*x^(2*k) + 15619*x^(3*k) + 15619*x^(4*k) + 4293*x^(5*k) + 247*x^(6*k) + x^(7*k))/(1 - x^k)^9, {k, 1, nmax}], {x, 0, nmax}], x]
%o A386784 (Magma) [0] cat [n^4*DivisorSigma(4, n): n in [1..35]]; // _Vincenzo Librandi_, Aug 03 2025
%Y A386784 Cf. A280022, A386783, A280025, A386785, A386786, A386787, A386788.
%Y A386784 Cf. A001159, A386749, A386747, A386748.
%K A386784 nonn,mult
%O A386784 0,3
%A A386784 _Vaclav Kotesovec_, Aug 02 2025