login
A153988
Number of planar n X n X n binary triangular grids symmetric both under 120 degree rotation and reflection with every one adjacent to exactly 2 other ones.
0
1, 1, 2, 2, 2, 4, 7, 7, 19, 30, 41, 111, 242, 341, 1198, 2798, 5288, 19451, 58386, 113037, 552176, 1717743, 4407296, 22107632, 91701868, 243757707, 1626825070, 6947686128, 24465641567, 168345671664, 954487204861, 3466462776895
OFFSET
0,3
CROSSREFS
Sequence in context: A005865 A176051 A245257 * A253059 A098705 A029866
KEYWORD
nonn
AUTHOR
R. H. Hardin Jan 04 2009
STATUS
approved