A006713 Number of 3-edge-colored connected trivalent graphs with 2n labeled nodes.

6, 480, 196560, 149869440, 208166112000, 470619551001600, 1622357050938624000, 8100931274981056512000, 56279222605087617687552000, 526611567858781597240688640000, 6462027944190599588931310387200000, 101691538301880025620001692844032000000

Offset: 2

Author

N. J. A. Sloane

Keywords

• nonn

References

• R. C. Read, Some Enumeration Problems in Graph Theory. Ph.D. Dissertation, Department of Mathematics, Univ. London, 1958.
• N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Links

• Andrew Howroyd, Table of n, a(n) for n = 2..50
• R. C. Read, Letter to N. J. A. Sloane, Feb 04 1971 (gives initial terms of this sequence)

Crossrefs

Cf. A006712 (for not necessarily connected graphs), A248362 (for the incorrect values). See also A002830, A002831, A002851.

Extensions

a(5)-a(6) corrected and a(7)-a(10) from Sean A. Irvine, Oct 05 2014

Terms a(11) and beyond from Andrew Howroyd, Dec 18 2017