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A003083 Sum a(n) x^n / n = log (1 + Sum g(n) x^n ), where g(n) is # graphs on n nodes (A000088).
(Formerly M2691)
0
1, 3, 7, 27, 106, 681, 5972, 88963, 2349727, 117165818, 11073706216, 1968717966417, 654366802299848, 406048824479878828, 470960717141418629512, 1023512961811602818909395, 4179821138595428450831985657, 32171971054480183600023612728841 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

REFERENCES

F. Harary and E. M. Palmer, Graphical Enumeration, Academic Press, NY, 1973, p. 91.

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

LINKS

Table of n, a(n) for n=1..18.

MATHEMATICA

nn=20; g=Sum[NumberOfGraphs[n]x^n, {n, 1, nn}]; Drop[Range[0, nn]CoefficientList[ Series[Log[1+g], {x, 0, nn}], x], 1]  (* Geoffrey Critzer, Oct 20 2012 *)

CROSSREFS

Sequence in context: A216174 A260464 A246313 * A062795 A062363 A242328

Adjacent sequences:  A003080 A003081 A003082 * A003084 A003085 A003086

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane.

STATUS

approved

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Last modified November 19 11:01 EST 2018. Contains 317350 sequences. (Running on oeis4.)