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

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn

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

Extensions

More terms and title clarified by Sean A. Irvine, Feb 02 2015