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A215765 Number of undirected labeled graphs on n nodes with exactly 5 cycle graphs as connected components.

%I A215765 #5 Aug 23 2012 21:06:16
%S A215765 1,15,140,1190,10857,109935,1222210,14771955,192855949,2705536834,
%T A215765 40597839100,648954464340,11010645610113,197646020548569,
%U A215765 3742573587799761,74560940574685875,1559079985774886316,34142131775027937276,781462189858194371736
%N A215765 Number of undirected labeled graphs on n nodes with exactly 5 cycle graphs as connected components.
%H A215765 Alois P. Heinz, <a href="/A215765/b215765.txt">Table of n, a(n) for n = 5..170</a>
%p A215765 T:= proc(n, k) option remember; `if`(k<0 or k>n, 0, `if`(n=0, 1,
%p A215765       add(binomial(n-1, i)*T(n-1-i, k-1)*ceil(i!/2), i=0..n-k)))
%p A215765     end:
%p A215765 a:= n-> T(n, 5):
%p A215765 seq (a(n), n=5..25);
%Y A215765 Column k=5 of A215771.
%K A215765 nonn
%O A215765 5,2
%A A215765 _Alois P. Heinz_, Aug 23 2012