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 A047805 #22 Feb 18 2023 07:30:07 %S A047805 1,288,189648,16845696,397610064,4630772160,34415914176,187485113088, %T A047805 814904105040,2975518758816,9486517914720,27053099888256, %U A047805 70486130167488,169930928938176,384163702086528 %N A047805 Duplicate of A008695. %C A047805 Original title: Theta series of Niemeier lattice of type E_6^4. %F A047805 This series is the q-expansion of 3/4 E_4(z)^3 + 1/4 E_6(z)^2. Cf. A004009, A013973. %t A047805 terms = 15; E4[q_] := 1 + 240 Sum[DivisorSigma[3, n]*q^(2 n), {n, 1, terms}]; E6[q_] := 1 - 504 Sum[DivisorSigma[5, n]*q^(2 n), {n, 1, terms}]; s = 3/4 E4[q]^3 + 1/4 E6[q]^2 + O[q]^(3 terms); Partition[ CoefficientList[s, q], 2][[All, 1]][[1 ;; terms]] (* _Jean-François Alcover_, Jul 06 2017 *) %Y A047805 Equal to theta series of A_11 D_7 E_6, cf. A008695 %K A047805 dead %O A047805 0,2 %A A047805 _N. J. A. Sloane_ %E A047805 More terms and formula in terms of Eisenstein series from _Daniel D. Briggs_, Nov 25 2011