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A215766
Number of undirected labeled graphs on n nodes with exactly 6 cycle graphs as connected components.
2
1, 21, 266, 2898, 31899, 375375, 4754200, 64566645, 936889954, 14477748285, 237514188730, 4124517063940, 75606129579493, 1459266319935423, 29585813267243475, 628724462015327265, 13976353234658809071, 324398325664769299713, 7848176443746842027187
OFFSET
6,2
LINKS
MAPLE
T:= proc(n, k) option remember; `if`(k<0 or k>n, 0, `if`(n=0, 1,
add(binomial(n-1, i)*T(n-1-i, k-1)*ceil(i!/2), i=0..n-k)))
end:
a:= n-> T(n, 6):
seq (a(n), n=6..25);
CROSSREFS
Column k=6 of A215771.
Sequence in context: A000770 A327507 A133105 * A320819 A360499 A228215
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Aug 23 2012
STATUS
approved