A211084 1/4 the number of n X n 0..3 symmetric matrices with every element equal to zero, two or three horizontal and vertical neighbors

1, 10, 228, 13227, 1888962, 662705112, 570731832303, 1205311139476404, 6235576486183465116, 78976030794422736761688

Offset

1,2

Links

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

Example

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

Crossrefs

Sequence in context: A052789 A092254 A211079 * A302095 A276019 A004702

Adjacent sequences: A211081 A211082 A211083 * A211085 A211086 A211087

Keyword

nonn

Author

R. H. Hardin Mar 31 2012

Status

approved