A006776 Number of n-step spirals on hexagonal lattice. (Formerly M2738)

1, 3, 8, 20, 47, 106, 230, 479, 973, 1924, 3712, 7021, 13034, 23780, 42732, 75703, 132360, 228664, 390611, 660296, 1105321, 1833358, 3014694, 4917036, 7958127, 12786252, 20401469, 32337878, 50936233, 79750436, 124149022, 192204697, 296001288, 453548269, 691574373, 1049590078

Offset

1,2

Comments

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

References

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

Links

Sean A. Irvine, Table of n, a(n) for n = 1..44

Sean A. Irvine, Java program (github)

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

G. Szekeres and A. J. Guttmann, Spiral self-avoiding walks on the triangular lattice, J. Phys. A 20 (1987), 481-493.

Crossrefs

Sequence in context: A101533 A138803 A048492 * A291097 A293883 A050231

Adjacent sequences: A006773 A006774 A006775 * A006777 A006778 A006779

Keyword

nonn

Author

N. J. A. Sloane.

Extensions

More terms from Sean A. Irvine, Aug 24 2019

Status

approved