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 A224729 #9 Apr 18 2013 02:04:04 %S A224729 1,2,14,138,1522,17740,213642,2628626,32833226,414697740,5282720764, %T A224729 67750624480,873653602902,11316723314858,147143725788662, %U A224729 1919360958676866,25105597581410410,329174706398378884,4325098764217263996,56934186664360843064 %N A224729 Central terms of the triangle in A059283. %C A224729 a(n) = A059283(2*n,n). %o A224729 (Haskell) %o A224729 a224729 n = a059283 (2*n) n %K A224729 nonn %O A224729 0,2 %A A224729 _Reinhard Zumkeller_, Apr 17 2013