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 A089448 #4 Mar 30 2012 18:36:39 %S A089448 1,4,48,841,18004,435654,11427992,317112363,9167951752,273436829602, %T A089448 8357069773840,260498528992976,8252868865615952,265043778330385821, %U A089448 8611226621063270068,282587565659572959007,9354553949064125991864 %N A089448 Diagonal of square table A089447, which lists the coefficients of x^n*y^k in f(x,y) that satisfies: f(x,y) = g(x,y) + xy*f(x,y)^4 and where g(x,y) satisfies: 1 + (x+y-1)*g(x,y) + xy*g(x,y)^2 = 0. %Y A089448 Cf. A089447 (table), A089449 (antidiagonal sums), A002293. %K A089448 nonn %O A089448 0,2 %A A089448 _Paul D. Hanna_, Nov 02 2003