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 A083411 #3 Mar 30 2012 16:49:44 %S A083411 0,1,9,79,765,8311,100989,1362439,20246445,328972471,5805917469, %T A083411 110645911399,2265191981325,49589790516631,1156201277261949, %U A083411 28605950745797959,748605590542359405,20661245832389468791,599820758571599742429,18272940402442730318119,582867486201919540724685 %N A083411 a(n) = Sum(((k-1)/2)*k!*Stirling_2(n,k),k=1..n). %F A083411 E.g.f.: (1/2)*( (1-exp(x))/(2-exp(x)) )^2. %Y A083411 Equals A083384(n)/n. %K A083411 nonn %O A083411 1,3 %A A083411 _N. J. A. Sloane_, Jun 08 2003