cp's OEIS Frontend

A215769 Number of undirected labeled graphs on n nodes with exactly 9 cycle graphs as connected components.

%I A215769 #5 Aug 23 2012 21:06:55
%S A215769 1,45,1155,23265,425139,7606599,138177325,2587238940,50238819917,
%T A215769 1014260971581,21309355619799,465938970674775,10598414480600407,
%U A215769 250610854305313887,6155065643528547592,156866857683142545246,4144501278635384568055,113404466183331483985825
%N A215769 Number of undirected labeled graphs on n nodes with exactly 9 cycle graphs as connected components.
%H A215769 Alois P. Heinz, <a href="/A215769/b215769.txt">Table of n, a(n) for n = 9..170</a>
%p A215769 T:= proc(n, k) option remember; `if`(k<0 or k>n, 0, `if`(n=0, 1,
%p A215769       add(binomial(n-1, i)*T(n-1-i, k-1)*ceil(i!/2), i=0..n-k)))
%p A215769     end:
%p A215769 a:= n-> T(n, 9):
%p A215769 seq (a(n), n=9..30);
%Y A215769 Column k=9 of A215771.
%K A215769 nonn
%O A215769 9,2
%A A215769 _Alois P. Heinz_, Aug 23 2012