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 A126780 #9 Dec 24 2012 02:06:30
%S A126780 24,360,5880,109200,2298744,54313560,1425878520,41215616640,
%T A126780 1301388272184,44580423767880,1647012735721080,65286028105225200,
%U A126780 2764048499876532984,124490422185142171320,5943580498312544073720
%N A126780 Number of functions f:{1,2,...,n}->{1,2,...,n} such that Im(f) contains 4 fixed elements.
%H A126780 Milan Janjic, <a href="http://www.pmfbl.org/janjic/">Enumerative Formulas for Some Functions on Finite Sets</a>
%F A126780 a(n)=n^n-4*(n-1)^n+6*(n-2)^n-4*(n-3)^n+(n-4)^n, (n=4,5,...)
%e A126780 a(7)=109200
%p A126780 a:=n->n^n-4*(n-1)^n+6*(n-2)^n-4*(n-3)^n+(n-4)^n;
%t A126780 Drop[Table[Sum[(-1)^k Binomial[4,k] (n-k)^n,{k,0,4}],{n,1,20}],3] (* _Geoffrey Critzer_, Dec 23 2012 *)
%K A126780 nonn
%O A126780 4,1
%A A126780 Aleksandar M. Janjic and _Milan Janjic_, Feb 18 2007