A007274 Walks on hexagonal lattice using each point at most twice. (Formerly M4222)

1, 6, 36, 216, 1260, 7206, 40650, 227256, 1262832, 6983730, 38470224, 211220814, 1156489782, 6317095284, 34435495872, 187380150468, 1018035642054

Offset

0,2

Comments

The hexagonal lattice is the familiar 2-dimensional lattice in which each point has 6 neighbors. This is sometimes called the triangular lattice.

Guttmann et al. has incorrect a(10) = 38470220, a(11) = 211220800, a(12) = 1156490000. - Sean A. Irvine, Dec 02 2017

References

A. J. Guttmann, C. Byrnes and N. E. Frankel, A generalized self-avoiding walk, J. Phys. A 17 (1984), L457-L461.

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

Links

Table of n, a(n) for n=0..16.

G. Nebe and N. J. A. Sloane, Home page for hexagonal (or triangular) lattice A2

Crossrefs

Cf. A001334, A007275.

Sequence in context: A124535 A267789 A228737 * A269616 A269580 A269432

Adjacent sequences: A007271 A007272 A007273 * A007275 A007276 A007277

Keyword

nonn,walk

Author

Simon Plouffe

Extensions

Title improved, a(10)-a(12) corrected, and a(15)-a(16) added by Sean A. Irvine, Dec 02 2017

Status

approved