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A174313 Number of n-step walks on hexagonal lattice (no points repeated, no adjacent points unless consecutive in path). 11
1, 6, 18, 54, 162, 474, 1398, 4074, 11898, 34554, 100302, 290322, 839382, 2422626, 6984342, 20110806, 57851358, 166258242, 477419658, 1369878582, 3927963138, 11255743434, 32235116502, 92267490414, 263968559874, 754837708494, 2157584748150, 6164626128066, 17606866229010 (list; graph; refs; listen; history; text; internal format)
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.

Fisher and Hiley give 290334 and 839466 as their last terms instead of 290322 and 839382 (see A002933).  Douglas McNeil confirms the correction on the seqfan list Nov 27 2010.

REFERENCES

N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).

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..28.

M. E. Fisher and B. J. Hiley, Configuration and free energy of a polymer molecule with solvent interaction, J. Chem. Phys., 34 (1961), 1253-1267.

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

CROSSREFS

Cf. A173380 for square lattice equivalent.

Sequence in context: A076941 A006779 A003208 * A002933 A016089 A099856

Adjacent sequences:  A174310 A174311 A174312 * A174314 A174315 A174316

KEYWORD

nonn,walk

AUTHOR

Joseph Myers, Nov 27 2010

EXTENSIONS

a(19)-a(28) from Bert Dobbelaere, Jan 02 2019

STATUS

approved

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Last modified September 21 08:38 EDT 2020. Contains 337268 sequences. (Running on oeis4.)