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

1,6

Links

Table of n, a(n) for n=1..31.

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

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.

Crossrefs

Cf. A003168, A007165.

Sequence in context: A027021 A013627 A248850 * A219212 A301904 A152119

Adjacent sequences: A294725 A294726 A294727 * A294729 A294730 A294731

Keyword

nonn

Author

Sean A. Irvine, Nov 07 2017

Status

approved