A014396 Number of loopless multigraphs with 6 nodes and n edges.

1, 1, 3, 8, 21, 52, 132, 313, 741, 1684, 3711, 7895, 16310, 32604, 63363, 119745, 220546, 396428, 696750, 1198812, 2022503, 3349574, 5452496, 8732932, 13776366, 21423968, 32872642, 49804323, 74560913, 110369469, 161639227

Offset

0,3

References

CRC Handbook of Combinatorial Designs, 1996, p. 650.

F. Harary and E. M. Palmer, Graphical Enumeration, Academic Press, NY, 1973, p. 88, (4.1.18).

J. L. Gross and J. Yellen, eds., Handbook of Graph Theory, CRC Press, 2004; p. 517.

Links

Andrew Howroyd, Table of n, a(n) for n = 0..1000

Mathematica

CoefficientList[Series[PairGroupIndex[SymmetricGroup[6], s]/.Table[s[i]->1/(1-x^i), {i, 1, Binomial[6, 2]}], {x, 0, 30}], x] (* Geoffrey Critzer, Oct 14 2012 *)

Prog

(PARI) concat([1], G(6, 40)) \\ See A191646 for G. - Andrew Howroyd, Mar 15 2020

Crossrefs

Row 6 of A192517.

Cf. A001399, A003082, A014395, A014397, A014398.

Sequence in context: A096770 A007835 A152086 * A170881 A039671 A267946

Adjacent sequences: A014393 A014394 A014395 * A014397 A014398 A014399

Keyword

nonn

Author

N. J. A. Sloane

Extensions

More terms and better description from Vladeta Jovovic, Dec 29 1999

Status

approved