A210924 Number of n X n 0..3 symmetric matrices with every element equal to zero, one or three horizontal and vertical neighbors, and new values 0..3 introduced in lower triangle row major order.

1, 2, 50, 5280, 1845589, 2131393730, 8110404963737, 101713393925588269, 4204356938900447492681, 572796548087149263352167089, 257205150385663723399847224344969

Offset

1,2

Links

Table of n, a(n) for n=1..11.

Example

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

Crossrefs

Sequence in context: A079198 A274485 A210919 * A355629 A203766 A197487

Adjacent sequences: A210921 A210922 A210923 * A210925 A210926 A210927

Keyword

nonn

Author

R. H. Hardin, Mar 29 2012

Status

approved