cp's OEIS Frontend

A215767 Number of undirected labeled graphs on n nodes with exactly 7 cycle graphs as connected components.

%I A215767 #5 Aug 23 2012 21:06:37
%S A215767 1,28,462,6300,82929,1128204,16187314,245722477,3944372432,
%T A215767 66863837040,1194908786890,22468992674310,443708326841383,
%U A215767 9184432111987960,198909290886899005,4499373643453767540,106128250525908452226,2606280798870785902866,66541442123879872392375
%N A215767 Number of undirected labeled graphs on n nodes with exactly 7 cycle graphs as connected components.
%H A215767 Alois P. Heinz, <a href="/A215767/b215767.txt">Table of n, a(n) for n = 7..170</a>
%p A215767 T:= proc(n, k) option remember; `if`(k<0 or k>n, 0, `if`(n=0, 1,
%p A215767       add(binomial(n-1, i)*T(n-1-i, k-1)*ceil(i!/2), i=0..n-k)))
%p A215767     end:
%p A215767 a:= n-> T(n, 7):
%p A215767 seq (a(n), n=7..25);
%Y A215767 Column k=7 of A215771.
%K A215767 nonn
%O A215767 7,2
%A A215767 _Alois P. Heinz_, Aug 23 2012