

A006778


Number of nstep spirals on hexagonal lattice.
(Formerly M2652)


0



1, 3, 7, 15, 31, 59, 110, 198, 347, 592, 997, 1641, 2666, 4266, 6741, 10525, 16268, 24882, 37717, 56683, 84504, 125031, 183716, 268125, 388873, 560647, 803723, 1146013, 1625731
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

1,2


COMMENTS

The hexagonal lattice is the familiar 2dimensional 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).
G. Szekeres and A. J. Guttmann, Spiral selfavoiding walks on the triangular lattice, J. Phys. A 20 (1987), 481493.


LINKS

Table of n, a(n) for n=1..29.
G. Nebe and N. J. A. Sloane, Home page for hexagonal (or triangular) lattice A2


CROSSREFS

Sequence in context: A229006 A023424 A276647 * A007574 A034480 A218281
Adjacent sequences: A006775 A006776 A006777 * A006779 A006780 A006781


KEYWORD

nonn,more


AUTHOR

N. J. A. Sloane.


STATUS

approved



