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 A002434 #20 Aug 14 2020 03:43:50 %S A002434 1,0,0,1640,119574,1497600,16733184,108081792,588805308,2544826368, %T A002434 9516533760,31328289720,92876121704,252846217728,638250227712, %U A002434 1511780699520,3387237774102,7228330481664 %N A002434 Theta series of Borcherds' 27-dimensional unimodular lattice T_27. %H A002434 G. C. Greubel, <a href="/A002434/b002434.txt">Table of n, a(n) for n = 0..1000</a> %H A002434 R. Bacher and B. B. Venkov, <a href="https://www-fourier.univ-grenoble-alpes.fr/?q=fr/content/reseaux-entiers-unimodulaires-sans-racine-en-dimension-27-et-28">Réseaux entiers unimodulaires sans racine en dimension 27 et 28</a>, in Réseaux euclidiens, designs sphériques et formes modulaires, pp. 212-267, Enseignement Math., Geneva, 2001. %H A002434 J. H. Conway and N. J. A. Sloane, <a href="https://www.researchgate.net/publication/46957856_Sphere_Packings_Lattices_and_Groups">Sphere Packings, Lattices and Groups</a>, Springer-Verlag, Preface to 3rd ed. %p A002434 th3^27-54*th3^19*delta8+216*th3^11*delta8^2-1024*th3^3*delta8^3 # (th3= A000122, delta8= A002408). %t A002434 terms = 18; QP = QPochhammer; th3 = EllipticTheta[3, 0, q]; delta8 = q*(QP[q]*(QP[q^4]/QP[q^2]))^8; s = th3^27 - 54*th3^19*delta8 + 216*th3^11*delta8^2 - 1024*th3^3*delta8^3 + O[q]^terms; CoefficientList[s, q] (* _Jean-François Alcover_, Jul 06 2017 *) %K A002434 nonn %O A002434 0,4 %A A002434 _N. J. A. Sloane_