A210898 Number of n X n 0..2 symmetric matrices with every element equal to zero or two horizontal and vertical neighbors, and new values 0..2 introduced in lower triangle row major order.

1, 3, 17, 199, 3494, 98664, 4322895, 299203520, 32406437104, 5516394350943, 1472647280151852, 617087491407309762, 405686597596735406852

Offset

1,2

Links

Table of n, a(n) for n=1..13.

Example

Some solutions for n=3:
..0..1..0....0..1..0....0..1..2....0..0..1....0..1..2....0..1..2....0..1..2
..1..0..1....1..2..1....1..2..1....0..0..2....1..2..0....1..0..0....1..2..1
..0..1..2....0..1..2....2..1..0....1..2..1....2..0..1....2..0..0....2..1..2

Crossrefs

Sequence in context: A202424 A335343 A133991 * A009494 A267659 A075271

Adjacent sequences: A210895 A210896 A210897 * A210899 A210900 A210901

Keyword

nonn,more

Author

R. H. Hardin, Mar 29 2012

Status

approved