A153987 Number of planar n X n X n binary triangular grids with mirror symmetry about one altitude with every one adjacent to exactly 2 other ones.

1, 1, 2, 3, 5, 12, 33, 97, 381, 1490, 7757, 42774, 307960, 2294754, 22718581, 231171797, 3121763126, 43651298703, 807916379400, 15440457456928, 391605380566734, 10243338678890245, 355535039683009851

Offset

0,3

Links

Table of n, a(n) for n=0..22.

Crossrefs

Sequence in context: A284910 A233231 A319912 * A228905 A369847 A306038

Adjacent sequences: A153984 A153985 A153986 * A153988 A153989 A153990

Keyword

nonn

Author

R. H. Hardin Jan 04 2009

Status

approved