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Search: id:A053549
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| A053549 |
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Number of labeled rooted connected graphs. |
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+0
5
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| 0, 1, 2, 12, 152, 3640, 160224, 13063792, 2012388736, 596666619648, 344964885948160, 392058233038486784, 880255154481199466496, 3916538634445633156373504, 34603083354426212294072477696, 607915214065957203519146330173440
(list; graph; listen)
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OFFSET
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0,3
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REFERENCES
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F. Harary and E. M. Palmer, Graphical Enumeration, Academic Press, NY, 1973, p. 10, R_p.
R. P. Stanley, Enumerative Combinatorics, Cambridge, Vol. 2, 1999; see Problem 5.20, G(x).
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LINKS
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T. D. Noe, Table of n, a(n) for n=0..50
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FORMULA
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E.g.f.: Sum(2^binomial(n, 2)*x^n/(n-1)!, n=1..31)/Sum(2^binomial(n, 2)*x^n/n!, n=0..31).
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MAPLE
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add(2^binomial(n, 2)*x^n/(n-1)!, n=1..31)/add(2^binomial(n, 2)*x^n/n!, n=0..31);
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CROSSREFS
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a(n)=n*A001187(n). Cf. A006125.
Sequence in context: A126345 A000795 A085628 this_sequence A139383 A130529 A075631
Adjacent sequences: A053546 A053547 A053548 this_sequence A053550 A053551 A053552
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com), Jan 16 2000
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