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 A131350 #7 May 15 2017 18:24:34 %S A131350 1,2,1,1,4,1,2,4,6,1,1,8,9,8,1,2,7,20,16,10,1,1,12,24,40,25,12,1,2,10, %T A131350 42,60,70,36,14,1,1,16,46,112,125,112,49,16,1,2,13,72,148,252,231,168, %U A131350 64,18,1 %N A131350 2*A007318 - A049310 as infinite lower triangular matrices. %C A131350 Row sums = A099036 starting (1, 3, 6, 13, 27, 56, 115,...). %e A131350 First few rows of the triangle are: %e A131350 1; %e A131350 2, 1; %e A131350 1, 4, 1; %e A131350 2, 4, 6, 1; %e A131350 1, 8, 9, 8, 1; %e A131350 2, 7, 20, 16, 10, 1; %e A131350 1, 12, 24, 40, 25, 12, 1; %e A131350 ... %Y A131350 Cf. A007318, A049310, A131350. %K A131350 nonn,tabl %O A131350 0,2 %A A131350 _Gary W. Adamson_, Jul 02 2007