A210901 Number of n X n 0..2 symmetric matrices with every element equal to zero, one or three horizontal and vertical neighbors, and new values 0..2 introduced in lower triangle row major order

1, 2, 20, 464, 22564, 2472584, 603871080, 327862785884, 395850912855384, 1063574508841830552, 6358546221961060404292, 84578736940287879637237736

Offset

1,2

Links

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

Example

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

Crossrefs

Sequence in context: A009160 A188811 A009252 * A274572 A292396 A274738

Adjacent sequences: A210898 A210899 A210900 * A210902 A210903 A210904

Keyword

nonn

Author

R. H. Hardin Mar 29 2012

Status

approved