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 A107868 #3 Mar 30 2012 18:36:46 %S A107868 1,2,6,35,330,4368,74613,1560780,38608020,1101716330,35607051480, %T A107868 1285063345176,51209646652255,2232785266876080,105710363656182600, %U A107868 5399936810873056584,295998326072989842600,17328840976366636057110 %N A107868 Column 0 of triangle A107867; a(n) = C( n*(n-1)/2 + n + 1, n). %o A107868 (PARI) a(n)=binomial(n*(n-1)/2+n+1,n) %Y A107868 Cf. A107867, A107869. %K A107868 nonn %O A107868 0,2 %A A107868 _Paul D. Hanna_, Jun 04 2005