A211086 1/4 the number of n X n 0..3 symmetric matrices with every element equal to zero, one, two or three horizontal and vertical neighbors

1, 16, 960, 229824, 219386880, 834532651008, 12650446296013824, 764188858823853957120, 183961835921396390619045888, 176476517080094726836047543951360

Offset

1,2

Links

R. H. Hardin, Table of n, a(n) for n = 1..13

Example

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

Crossrefs

Sequence in context: A211081 A197449 A264640 * A187802 A181199 A024301

Adjacent sequences: A211083 A211084 A211085 * A211087 A211088 A211089

Keyword

nonn

Author

R. H. Hardin Mar 31 2012

Status

approved