A210927 Number of n X n 0..3 symmetric matrices with every element equal to zero, one, two or three horizontal and vertical neighbors, and new values 0..3 introduced in lower triangle row major order

1, 5, 172, 38444, 36567600, 139088906848, 2108407726540016, 127364809805575916736, 30660305986899859448541568, 29412752846682454724638291977856

Offset

1,2

Links

R. H. Hardin, Table of n, a(n) for n = 1..15

Example

Some solutions for n=4
..0..0..1..1....0..1..2..1....0..0..2..1....0..0..1..0....0..1..1..0
..0..0..2..2....1..1..2..1....0..1..3..3....0..1..2..2....1..0..0..1
..1..2..3..1....2..2..0..3....2..3..2..0....1..2..2..0....1..0..0..1
..1..2..1..0....1..1..3..3....1..3..0..0....0..2..0..2....0..1..1..0

Crossrefs

Sequence in context: A206393 A220640 A198711 * A139986 A354573 A123111

Adjacent sequences: A210924 A210925 A210926 * A210928 A210929 A210930

Keyword

nonn

Author

R. H. Hardin Mar 29 2012

Status

approved