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 A056947 #13 Jul 11 2021 03:42:35 %S A056947 1,24,195984,16779168,397998672,4629497040,34417510848,187489533504, %T A056947 814881802320,2975548760568,9486548517600,27052958750688, %U A056947 70486228096704,169931081461008,384163595996544,820166650027200,1668890114013264,3249630946490544,6096882726702288 %N A056947 Theta series of nonexistent Niemeier lattice of Coxeter number 1. %D A056947 J. H. Conway and N. J. A. Sloane, Sphere Packings, Lattices and Groups, Springer-Verlag, 1988. %H A056947 Andy Huchala, <a href="/A056947/b056947.txt">Table of n, a(n) for n = 0..20000</a> %F A056947 E_12(z)+(24h-c12)*D(12) where D(12) is unique cusp form of weight 12, c12=(2*Pi)^12/(zeta(12)*gamma(12)) and h=1. %F A056947 a(n) = (A029828(n) - 48936*A000594(n))/691. - _Andy Huchala_, Jul 11 2021 %e A056947 G.f.: 1 + 24*q + 195984*q^2 + 16779168*q^3 + ... %o A056947 (Sage) %o A056947 d = CuspForms(1, 12).0.q_expansion(20); %o A056947 e =(eisenstein_series_qexp(12,20, normalization='integral')) %o A056947 list(e/691-(48936/691)*d) # _Andy Huchala_, Jul 10 2021 %Y A056947 Cf. A029828, A000594. %K A056947 nonn %O A056947 0,2 %A A056947 Kok Seng Chua (chuaks(AT)ihpc.nus.edu.sg), Jul 17 2000