A006818 Trails of length n on hexagonal lattice.

1, 6, 30, 150, 738, 3570, 17118, 81498, 385710, 1817046, 8528478, 39903462, 186198642, 866861394, 4027766490, 18681900270, 86518735722, 400136695074, 1848320799438, 8528448008214

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn
• walk
• more

Comments

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

References

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

Links

• A. J. Guttmann, Lattice trails II: numerical results, J. Phys. A 22 (1989), 575-588.
• G. Nebe and N. J. A. Sloane, Home page for hexagonal (or triangular) lattice A2

Extensions

a(17)-a(19) from Sean A. Irvine, Aug 15 2020