A007170 Number of Q-graphs with 2n edges.
0, 1, 2, 8, 48, 328, 2335, 17133, 128262, 975547, 7518282, 58582564, 460769228, 3653385453, 29170737927, 234350263419, 1892956305974, 15364355580327, 125247311808502, 1024983176867450, 8417817643684208, 69355110426227296
Offset: 1
Keywords
References
- N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
Links
- R. C. Read, On the enumeration of a class of plane multigraphs, Aequat. Math. 31 (1986) no 1, 47-63.
Formula
Extensions
a(9) corrected and more terms from Sean A. Irvine, Nov 07 2017