A294724 Number of Q graphs with 2*n vertices rooted at an internal edge.

0, 0, 0, 1, 11, 96, 785, 6283, 49987, 397768, 3174084, 25426290, 204538114, 1652327820, 13402442651, 109129475455, 891793354235, 7312118010384, 60141701374424, 496095022537998, 4103183675407098, 34022136992384720

Offset

1,5

Links

Table of n, a(n) for n=1..22.

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

Formula

G.f.: P(x) * (B(x) - x)^2 where P(x) is the g.f. for A003169 and B(x) is the g.f. for A003168.

Crossrefs

Cf. A003168, A003169.

Sequence in context: A271632 A055286 A081041 * A115351 A154997 A137017

Adjacent sequences: A294721 A294722 A294723 * A294725 A294726 A294727

Keyword

nonn

Author

Sean A. Irvine, Nov 07 2017

Status

approved