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 A386816 #4 Aug 03 2025 16:07:42
%S A386816 1,672,145152,8663424,-337036224,-6505531200,40579467264,
%T A386816 1996981485312,25931378854080,210242562994464,1273050737441280,
%U A386816 6245511315490944,26057670474216192,95466371280176064,314217417062264832,945050326572360960,2631525623493208512,6854684254893824832
%N A386816 Coefficients in q-expansion of E_2^2 * E_4^3, where E_2 and E_4 are respectively the Eisenstein series A006352 and A004009.
%t A386816 terms = 20;
%t A386816 E2[x_] = 1 - 24*Sum[k*x^k/(1 - x^k), {k, 1, terms}];
%t A386816 E4[x_] = 1 + 240*Sum[k^3*x^k/(1 - x^k), {k, 1, terms}];
%t A386816 CoefficientList[Series[E2[x]^2*E4[x]^3, {x, 0, 20}], x]
%Y A386816 Cf. A006352, A004009, A386787.
%K A386816 sign
%O A386816 0,2
%A A386816 _Vaclav Kotesovec_, Aug 03 2025