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 A056949 #3 Feb 24 2006 03:00:00
%S A056949 1,2,0,-2,24,52,0,32556,195984,261626,0,3736682,16779168,18348900,0,
%T A056949 103018596,397998672,376729140,0,1334328534,4629497040,3937811168,0,
%U A056949 10792678852,34417510848,26962705262,0,62783490188,187489533504,138066125924,0,287105737648,814881802320
%N A056949 J(1)*theta3(z) where J(1) is the series given by A056948.
%C A056949 a(4n) gives the series A056948(n). It seems only a(3) is negative. What are a(4n+1), a(4n+3)?
%D A056949 Eichler and Zagier, The Theory of Jacobi form, Birkhauser, 1985
%F A056949 (E_8*E_{4, 1}-56*E_{12, 1})*theta_3(z)
%Y A056949 Cf. A056947, A056948.
%K A056949 sign
%O A056949 0,2
%A A056949 Kok Seng Chua (chuaks(AT)ihpc.nus.edu.sg), Jul 17 2000