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 A124889 #3 Mar 30 2012 18:37:01 %S A124889 1,2,9,44,235,1296,7329,42104,244719,1434840,8470517,50280372, %T A124889 299806572,1794382548,10773855210,64865425760,391457133672, %U A124889 2367314649522,14342441005900,87035702613500,528938145043707,3218713327609648 %N A124889 Central terms of triangle A124328; a(n) = A124328(2n+1,n+1) for n>=0. %F A124889 a(n) = (n+1)*A124890(n). %Y A124889 Cf. A124328, A124889, A124890, A124891. %K A124889 nonn %O A124889 0,2 %A A124889 _Paul D. Hanna_, Nov 12 2006