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%I M2691 #20 Aug 11 2020 10:07:02
%S 1,3,7,27,106,681,5972,88963,2349727,117165818,11073706216,
%T 1968717966417,654366802299848,406048824479878828,
%U 470960717141418629512,1023512961811602818909395,4179821138595428450831985657,32171971054480183600023612728841
%N Sum a(n) x^n / n = log (1 + Sum g(n) x^n ), where g(n) is # graphs on n nodes (A000088).
%D F. Harary and E. M. Palmer, Graphical Enumeration, Academic Press, NY, 1973, p. 91.
%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%F a(n) = Sum_{d|n} d * A001349(d). - _Andrey Zabolotskiy_, Aug 11 2020
%t 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 *)
%Y Cf. A000088, A001349.
%K nonn,easy
%O 1,2
%A _N. J. A. Sloane_
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