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 A124819 #2 Mar 30 2012 18:59:18 %S A124819 1,2,1,3,5,1,4,15,8,1,5,35,36,11,1,6,70,120,66,14,1,7,126,330,286,105, %T A124819 17,1,8,210,792,1001,560,153,20,1,9,330,1716,3003,2380,969,210,23,1, %U A124819 10,495,3432,8008,8568,4845,1540,276 %N A124819 Number triangle T(n,k)=C(n+2k+1,3k+1). %C A124819 Row sums are A124820. Diagonal sums are A052921. Inverse is A124821. %F A124819 Riordan array (1/(1-x)^2,x/(1-x)^3) %e A124819 Triangle begins %e A124819 1, %e A124819 2, 1, %e A124819 3, 5, 1, %e A124819 4, 15, 8, 1, %e A124819 5, 35, 36, 11, 1, %e A124819 6, 70, 120, 66, 14, 1, %e A124819 7, 126, 330, 286, 105, 17, 1, %e A124819 8, 210, 792, 1001, 560, 153, 20, 1 %K A124819 easy,nonn,tabl %O A124819 0,2 %A A124819 _Paul Barry_, Nov 08 2006