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A182100 The number of connected simple labeled graphs with <= n nodes. 1
1, 2, 4, 11, 65, 974, 31744, 2069971, 267270041, 68629753650, 35171000942708, 36024807353574291, 73784587576805254665, 302228602363365451957806, 2475873310144021668263093216, 40564787336902311168400640561099 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

G. C. Greubel, Table of n, a(n) for n = 0..80

FORMULA

a(n) = Sum_{i=0..n} binomial(n,i)*A001187(i).

E.g.f.: exp(x)*A(x) where A(x) is e.g.f. for A001187.

MATHEMATICA

nn = 15; g = Sum[2^Binomial[n, 2] x^n/n!, {n, 0, nn}]; Range[0, nn]! CoefficientList[Series[Exp[x] (Log[g] + 1), {x, 0, nn}], x]

CROSSREFS

Sequence in context: A173312 A156434 A007903 * A006894 A193565 A198864

Adjacent sequences:  A182097 A182098 A182099 * A182101 A182102 A182103

KEYWORD

nonn

AUTHOR

Geoffrey Critzer, Apr 11 2012

STATUS

approved

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Last modified August 24 18:52 EDT 2019. Contains 326295 sequences. (Running on oeis4.)