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 A131398 #2 Mar 30 2012 17:25:22 %S A131398 1,1,1,2,4,1,2,8,7,1,2,11,17,10,1,2,14,29,29,13,1,2,17,44,59,44,16,1, %T A131398 2,20,62,104,104,62,19,1,2,23,83,167,209,167,83,22,1,2,26,107,251,377, %U A131398 377,251,107,25,1 %N A131398 3*A007318 - A097806 - A000012. %C A131398 Row sums = A077802, (1, 2, 7, 18, 41, 88,...). %F A131398 3*A007318 - A097806 - A000012 as infinite lower triangular matrices. %e A131398 First few rows of the triangle are: %e A131398 1; %e A131398 1, 1; %e A131398 2, 4, 1; %e A131398 2, 8, 7, 1; %e A131398 2, 11, 17, 10, 1; %e A131398 2, 14, 29, 29, 13, 1; %e A131398 ... %Y A131398 Cf. A007318, A097806, A000012, A077802. %K A131398 nonn,tabl %O A131398 0,4 %A A131398 _Gary W. Adamson_, Jul 05 2007