Voozh

A005979

Number of Hamiltonian rooted triangulations with n internal nodes and 5 external nodes.

5, 45, 420, 4130, 42480, 453350, 4986860, 56251230, 648055650, 7601584050, 90556803600, 1093417607850, 13359234113250, 164935358510470, 2055350730457020, 25827268868350690, 326989527294142480, 4168165020885948440, 53462092704596804720, 689613220013827480620

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,1

REFERENCES

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

LINKS

Peter J. Taylor, Table of n, a(n) for n = 0..500

P. N. Rathie, The enumeration of Hamiltonian polygons in rooted planar triangulations, Discrete Math., 6 (1973), 163-168.

FORMULA

a(n) = f(n, 5) where f(n, k) is defined in A003122. - Sean A. Irvine, Feb 02 2015

PROG

(C#) See A003122