A153989 Number of planar n X n X n binary triangular grids with every one adjacent to exactly 2 other ones.

1, 1, 2, 5, 11, 46, 267, 1767, 17587, 243760, 4437947, 112889388, 3947281130, 187476143214, 12242161648191, 1095392081180001, 134002137948473492, 22462563463091094957, 5156385913433257078626

Offset

0,3

Links

Table of n, a(n) for n=0..18.

Crossrefs

Sequence in context: A128231 A088148 A088149 * A160859 A106887 A236044

Adjacent sequences: A153986 A153987 A153988 * A153990 A153991 A153992

Keyword

nonn

Author

R. H. Hardin Jan 04 2009

Status

approved