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 A004671 #12 Oct 26 2023 00:58:23 %S A004671 1,0,39600,87859200,20779902000,1441891123200,46065617928000, %T A004671 861717856665600,10894640750334000,102119813013504000, %U A004671 755967560945968800,4623420024622080000,24151651608982497600,110516220812493619200 %N A004671 Theta series of extremal even unimodular lattice in dimension 40. %D A004671 J. H. Conway and N. J. A. Sloane, "Sphere Packings, Lattices and Groups", Springer-Verlag, p. 195. %H A004671 Andy Huchala, <a href="/A004671/b004671.txt">Table of n, a(n) for n = 0..20000</a> %F A004671 a(n) = A282015(n) - 1200 * A037945(n) - _Andy Huchala_, May 07 2021 %e A004671 G.f.: 1 + 39600*q^2 + 87859200*q^3 + ... %o A004671 (Sage) %o A004671 e4 = eisenstein_series_qexp(4,20,normalization = "integral"); %o A004671 delta = CuspForms(1,12).0.q_expansion(20); %o A004671 e4^5-1200*e4^2*delta # _Andy Huchala_, May 07 2021 %K A004671 nonn %O A004671 0,3 %A A004671 _N. J. A. Sloane_