A007275 Walks on hexagonal lattice using each point at most three times. (Formerly M4223)

1, 6, 36, 216, 1296, 7776, 46440, 276054, 1633848, 9633366, 56616132, 331847118, 1940715960, 11327957196, 66010769382, 384094025382, 2231978658906

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) = 56616140, a(11) = 331847200, and a(12) = 1940717000. - Sean A. Irvine, Dec 03 2017

References

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.

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

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

Crossrefs

Cf. A001334, A007274.

Sequence in context: A250358 A126634 A216128 * A206452 A215748 A000400

Adjacent sequences: A007272 A007273 A007274 * A007276 A007277 A007278

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 03 2017

Status

approved