A210919 Number of n X n 0..3 symmetric matrices with every element equal to zero or one horizontal and vertical neighbor, and new values 0..3 introduced in lower triangle row major order

1, 2, 50, 5036, 1650722, 1726180511, 5772723512117, 61704243727319597, 2108342605082097217766, 230275999931688657463304318, 80396959992514189225966415632361

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..2..0....0..1..2..0....0..1..1..3....0..1..0..3
..1..2..0..2....1..0..2..1....1..0..3..0....1..2..0..3....1..2..0..2
..0..0..3..0....2..2..1..0....2..3..2..3....1..0..3..2....0..0..3..0
..1..2..0..3....0..1..0..1....0..0..3..2....3..3..2..1....3..2..0..3

Crossrefs

Sequence in context: A356611 A079198 A274485 * A210924 A355629 A203766

Adjacent sequences: A210916 A210917 A210918 * A210920 A210921 A210922

Keyword

nonn

Author

R. H. Hardin Mar 29 2012

Status

approved