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 A069657 #3 Mar 30 2012 16:49:19 %S A069657 0,1,2,6,24,115,628,3818,25455,183968,1428184,11824098,103794727, %T A069657 961461179,9360372700,95448502365,1016413911387,11273822075837, %U A069657 129950445723958,1553488011957986,19225242250821071,245899882175001580,3245812116097119188,44155099624566615247 %N A069657 Sum( S(n,k) * M(k-1), k=1..n), where S(n,k) = Stirling numbers of the second kind, M(n) = Motzkin numbers, A001006. %Y A069657 Cf. A006531, A001006. %K A069657 nonn %O A069657 0,3 %A A069657 _N. J. A. Sloane_, Jun 06 2002