

A261834


Number of nstep adjacent expansions on the hexagonal (honeycomb) lattice. Holes allowed.


1




OFFSET

0,2


COMMENTS

Initially only one cell C[0] is occupied on the lattice.
Then, for each i of (1..n), C[i] is chosen among the free cells adjacent to at least one of (C[0],..,C[i1]).
a(n) is the number of distinct (C[1],..,C[n]).


LINKS

Table of n, a(n) for n=0..9.
Francois Alcover, tree


EXAMPLE

a(1) = 6 because a point has 6 neighbors on the hex grid.
a(2) = 48 = a(1) * 8 because a twocell group has 8 free neighbors.


CROSSREFS

Cf. A007846 (same principle but on the rectangular lattice).
Cf. A001334.
Sequence in context: A085457 A188911 A319292 * A226740 A244509 A105627
Adjacent sequences: A261831 A261832 A261833 * A261835 A261836 A261837


KEYWORD

nonn,more


AUTHOR

Francois Alcover, Mar 24 2016


EXTENSIONS

More terms from Francois Alcover, Apr 29 2016
Rephrasing and culling comments from Francois Alcover, Apr 29 2016
Added crossref to A007846 from Francois Alcover, May 01 2016


STATUS

approved



