A210899 Number of n X n 0..2 symmetric matrices with every element equal to one or two horizontal and vertical neighbors, and new values 0..2 introduced in lower triangle row major order

0, 1, 2, 36, 1044, 74379, 10881920, 3566285692, 2524146683822, 3922290803244487, 13291420623117002040, 98512903545177272401383

Offset

1,3

Links

Table of n, a(n) for n=1..12.

Example

Some solutions for n=4
..0..0..1..1....0..0..1..0....0..0..1..0....0..0..1..2....0..0..0..0
..0..0..2..1....0..1..1..0....0..0..1..0....0..1..1..2....0..1..1..1
..1..2..2..1....1..1..2..2....1..1..1..2....1..1..0..0....0..1..2..2
..1..1..1..1....0..0..2..2....0..0..2..2....2..2..0..0....0..1..2..2

Crossrefs

Sequence in context: A209036 A375839 A305596 * A302903 A259467 A003092

Adjacent sequences: A210896 A210897 A210898 * A210900 A210901 A210902

Keyword

nonn

Author

R. H. Hardin Mar 29 2012

Status

approved