%I A081064
%S A081064 1,1,2,1,6,12,6,1,12,60,152,186,108,24,1,20,180,940,3050,6180,7960,6540,
%T A081064 3330,960,120,1,30,420,3600,20790,83952,240480,496680,750810,838130,
%U A081064 691020,416160,178230,51480,9000,720,1,42,840,10570,93030,601944
%N A081064 Number of labeled acyclic digraphs with n nodes and k arcs.
%C A081064 Row sums give A003024.
%F A081064 1 = 1*exp(-x)+1*exp(-(1+y)*x)*x/1!+(2*y+1)*exp(-(1+y)^2*x)*x^2/2!+(6*y^3+12*y^2+6*y+1)*exp(-(1+y)^3*x)*x^3/
               3!+ (24*y^6+108*y^5+186*y^4+152*y^3+60*y^2+12*y+1)*exp(-(1+y)^4*x)*x^4/
               4!+(120*y^10+960*y^9+3330*y^8+6540*y^7+7960*y^6+6180*y^5+3050*y^4+940*y^3+180*y^2+20*y+1)*exp(-(1+y)^5*x)\
               *x^5/5!+... - Vladeta Jovovic (vladeta(AT)eunet.rs), Jun 07 2005
%e A081064 1; 1,2; 1,6,12,6; 1,12,60,152,186,108,24; ...
%Y A081064 Sequence in context: A106192 A113025 A113216 this_sequence A128534 A002562 
               A136456
%Y A081064 Adjacent sequences: A081061 A081062 A081063 this_sequence A081065 A081066 
               A081067
%K A081064 easy,nonn
%O A081064 1,3
%A A081064 Vladeta Jovovic (vladeta(AT)eunet.rs), Apr 15 2003