

A007275


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


1



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

0,2


COMMENTS

The hexagonal lattice is the familiar 2dimensional 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 selfavoiding walk, J. Phys. A 17 (1984), L457L461.
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



