A210925 Number of n X n 0..3 symmetric matrices with every element equal to zero, two or three horizontal and vertical neighbors, and new values 0..3 introduced in lower triangle row major order

1, 3, 39, 2212, 314852, 110451021, 95121973827, 200885189935045, 1039262747697700932, 13162671799070468638683

Offset

1,2

Links

Table of n, a(n) for n=1..10.

Example

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

Crossrefs

Sequence in context: A015017 A210921 A290516 * A300046 A267624 A342178

Adjacent sequences: A210922 A210923 A210924 * A210926 A210927 A210928

Keyword

nonn

Author

R. H. Hardin Mar 29 2012

Status

approved