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 A008431 #14 Oct 16 2018 08:24:28 %S A008431 1,144,2034,7392,22608,44640,93984,141120,262386,343536,557280,703584, %T A008431 1068384,1234080,1851264,2057280,2884176,3231936,4428242,4639392, %U A008431 6455520,6670272,8814816,9320256,12065568,12152880,16161120,16124544,20496960,20906208,26378880,25736832 %N A008431 Theta series of D_9 lattice. %D A008431 J. H. Conway and N. J. A. Sloane, "Sphere Packings, Lattices and Groups", Springer-Verlag, p. 118. %H A008431 Seiichi Manyama, <a href="/A008431/b008431.txt">Table of n, a(n) for n = 0..10000</a> %F A008431 Expansion of 1/2 (EllipticTheta(3, 0, q)^9 + EllipticTheta(4, 0, q)^9) (formula given by Mathematica's LatticeData(D9)). - _Jean-François Alcover_, Jul 07 2017 %t A008431 terms = 24; s = 1/2 (EllipticTheta[3, 0, q]^9 + EllipticTheta[4, 0, q]^9) + O[q]^(2 terms); CoefficientList[s, q^2] (* _Jean-François Alcover_, Jul 07 2017 *) %K A008431 nonn,easy %O A008431 0,2 %A A008431 _N. J. A. Sloane_ %E A008431 More terms from _Seiichi Manyama_, Oct 16 2018