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A215857 Number of simple labeled graphs on n nodes with exactly 7 connected components that are trees or cycles. 3
1, 28, 714, 17220, 424809, 11002068, 303874714, 9016296289, 288135739892, 9913826194272, 366486926833846, 14513217676764534, 613646633464214863, 27609928896732666760, 1317652578222779606269, 66497975770225498765728, 3538905411811229060814213 (list; graph; refs; listen; history; text; internal format)
OFFSET

7,2

LINKS

Alois P. Heinz, Table of n, a(n) for n = 7..145

EXAMPLE

a(8) = 28: each graph has one 2-node tree and 6 1-node trees and C(8,2) = 28.

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)*

      `if`(i<2, 1, i!/2 +(i+1)^(i-1)), i=0..n-k)))

    end:

a:= n-> T(n, 7):

seq(a(n), n=7..25);

CROSSREFS

Column k=7 of A215861.

The unlabeled version is A215987.

Sequence in context: A160141 A331476 A239408 * A185987 A004293 A012808

Adjacent sequences:  A215854 A215855 A215856 * A215858 A215859 A215860

KEYWORD

nonn

AUTHOR

Alois P. Heinz, Aug 26 2012

STATUS

approved

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Last modified February 28 01:49 EST 2020. Contains 332319 sequences. (Running on oeis4.)