A211036 1/3 the number of (2n)X(2n) 0..2 symmetric matrices with every element equal to two horizontal and vertical neighbors

1, 6, 70, 1584, 69094, 5804980, 937523156, 290938653352, 173346851987198

Offset

1,2

Links

Table of n, a(n) for n=1..9.

Example

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

Crossrefs

Sequence in context: A036361 A365057 A182563 * A284215 A050788 A241883

Adjacent sequences: A211033 A211034 A211035 * A211037 A211038 A211039

Keyword

nonn

Author

R. H. Hardin Mar 30 2012

Status

approved