A007274 Walks on hexagonal lattice using each point at most twice.

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

Offset: 0

Author

Simon Plouffe

Keywords

• nonn
• walk

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

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

Crossrefs

Cf. A001334, A007275.

Extensions

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