A294728 Number of Q graphs with 2*n vertices symmetrical about a distinguished edge.

0, 0, 0, 1, 1, 6, 7, 37, 47, 242, 324, 1658, 2300, 11764, 16741, 85741, 124383, 638250, 939880, 4832446, 7202214, 37101556, 55842670, 288180066, 437325262, 2260516372, 3454370352, 17881862308, 27489383818, 142491830992, 220185726817

Offset: 1

Author

Sean A. Irvine, Nov 07 2017

Keywords

• nonn

Links

• R. C. Read, On the enumeration of a class of plane multigraphs, Aequat. Math. 31 (1986) no 1, 47-63.

Crossrefs

Cf. A003168, A007165.

Formula

G.f.: H(x) * (B(x^2) - x^2) where H(x) is the g.f. for A007165 and B(x) is the g.f. for A003168.