A210905 Number of n X n 0..2 symmetric matrices with every element equal to zero or one horizontal and vertical neighbors, and new values 0..2 introduced in lower triangle row major order

1, 2, 24, 552, 27204, 2812168, 611509240, 279902590168, 269562004096692, 546187771866465456, 2328406266027562097220, 20883572160878878738558896, 394075725737300936910238275696

Offset

1,2

Links

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

Example

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

Crossrefs

Sequence in context: A054946 A046744 A000186 * A012113 A156525 A170904

Adjacent sequences: A210902 A210903 A210904 * A210906 A210907 A210908

Keyword

nonn

Author

R. H. Hardin Mar 29 2012

Status

approved