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 A028376 #7 Aug 02 2015 10:45:08 %S A028376 0,0,1,0,1,2,0,2,3,5,0,5,7,9,14,0,14,19,23,28,42,0,42,56,66,76,90,132, %T A028376 0,132,174,202,227,255,297,429,0,429,561,645,715,785,869,1001,1430,0, %U A028376 1430,1859,2123,2333,2529,2739,3003,3432,4862,0,4862,6292,7150 %N A028376 Triangle read by rows: T(n,m) = Sum Catalan(n-k)*Catalan(k), k=0..m. %e A028376 0; %e A028376 0,1; %e A028376 0,1,2; %e A028376 0,2,3,5; %e A028376 0,5,7,9,14; %e A028376 0,14,19,23,28,42; ... %Y A028376 See A028364 for a better version. Cf. A028377, A028378. %K A028376 tabl,nonn,easy %O A028376 0,6 %A A028376 _Wouter Meeussen_