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 A217580 #12 Oct 24 2012 19:16:59
%S A217580 1,0,1,3,0,1,54,9,0,1,3861,216,18,0,1,1028700,19305,540,30,0,1,
%T A217580 1067510583,6172200,57915,1080,45,0,1,4390552197234,7472574081,
%U A217580 21602700,135135,1890,63,0,1,72022439672173161,35124417577872,29890296324,57607200,270270,3024,84,0,1
%N A217580 Triangular array read by rows. T(n,k) is the number of labeled digraphs on n nodes with exactly k isolated nodes. 0<=k<=n.
%C A217580 Column k=0 is A054545.
%F A217580 E.g.f.: exp(y*x)*A(x) where A(x) is the e.g.f. for A054545.
%e A217580 1;
%e A217580 0, 1;
%e A217580 3, 0, 1;
%e A217580 54, 9, 0, 1;
%e A217580 3861, 216, 18, 0, 1;
%e A217580 1028700, 19305, 540, 30, 0, 1;
%e A217580 1067510583, 6172200, 57915, 1080, 45, 0, 1;
%t A217580 nn=6; s=Sum[2^(2 Binomial[n,2])x^n/n!, {n,0,nn}]; Range[0,nn]! CoefficientList[Series[Exp[y x] s/Exp[x], {x,0,nn}], {x,y}] //Grid
%K A217580 nonn,tabl
%O A217580 0,4
%A A217580 _Geoffrey Critzer_, Oct 07 2012