A210930 Number of n X n 0..3 symmetric matrices with every element equal to one, two or four horizontal and vertical neighbors, and new values 0..3 introduced in lower triangle row major order.

0, 1, 2, 64, 4730, 1354791, 943637970, 1907539841676, 10349004212065264, 156102455896727660205

Offset

1,3

Links

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

Example

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

Crossrefs

Sequence in context: A187548 A300640 A054956 * A263185 A155957 A085535

Adjacent sequences: A210927 A210928 A210929 * A210931 A210932 A210933

Keyword

nonn

Author

R. H. Hardin, Mar 29 2012

Extensions

Name corrected by Andrew Howroyd, Mar 25 2025

Status

approved