A380242 Number of rooted 6-regular planar maps with n vertices.

1, 5, 100, 3000, 110000, 4550000, 204000000, 9690000000, 480700000000, 24667500000000, 1300650000000000, 70122000000000000, 3851316000000000000, 214878980000000000000, 12151776800000000000000, 695297229000000000000000, 40193385270000000000000000, 2344614140750000000000000000

Offset

0,2

Links

Andrew Howroyd, Table of n, a(n) for n = 0..200

Formula

a(n) = 2*10^n*(3*n)!/(n!*(2*n + 2)!).

Prog

(PARI) a(n) = 2*10^n*(3*n)!/(n!*(2*n + 2)!)

Crossrefs

Column k=3 of A380241.

Cf. A000168, A380243.

Sequence in context: A128784 A369535 A078534 * A141120 A384017 A123668

Adjacent sequences: A380239 A380240 A380241 * A380243 A380244 A380245

Keyword

nonn

Author

Andrew Howroyd, Jan 22 2025

Status

approved