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 A001188 Number of even graphs with n edges. (Formerly M1892 N0746) 2
 1, 2, 8, 60, 672, 9953, 184557, 4142631, 109813842, 3373122370, 118280690398, 4678086540493, 206625802351035, 10107719377251109, 543762148079927802, 31975474310851749920, 2044501883873268414092, 141485408653554069693421 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS a(n) appears to be [A060639(n) + 1] / 2. - Ralf Stephan, Aug 21 2004 REFERENCES D. G. Cantor, personal communication. N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence). N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). LINKS Sean A. Irvine, Table of n, a(n) for n = 1..50 E. N. Gilbert, Enumeration of labelled graphs, Canad. J. Math., 8 (1956), 405-411. E. N. Gilbert, Enumeration of labelled graphs (Annotated scanned copy) R. W. Robinson, First 50 terms of A1187 and A1188 MAPLE with(combinat); g:=k->sum(stirling2(k, j), j=0..k)^2; egf:=series((exp(x)-1+log(1+sum(g(k)*x^k/k!, k=1..infinity)))/2, x, 20); seq(n!*coeff(egf, x, n), n=1..20); # Sean A. Irvine, Mar 22 2012 CROSSREFS Sequence in context: A052622 A303672 A303062 * A303532 A113145 A293379 Adjacent sequences:  A001185 A001186 A001187 * A001189 A001190 A001191 KEYWORD nonn AUTHOR EXTENSIONS More terms from Sean A. Irvine, Mar 21 2012 STATUS approved

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Last modified January 21 11:21 EST 2019. Contains 319354 sequences. (Running on oeis4.)