A211052 1/3 the number of n X n 0..2 symmetric matrices with every element equal to one, two or three horizontal and vertical neighbors

0, 1, 9, 239, 14669, 2313041, 915560157, 915512113455, 2309733753013069, 14705975948890342013, 236286306641789616616527, 9580759647090339471565196845, 980341335177418943590433413869387

Offset

1,3

Links

R. H. Hardin, Table of n, a(n) for n = 1..14

Example

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

Crossrefs

Sequence in context: A157569 A279492 A297747 * A085799 A278858 A274789

Adjacent sequences: A211049 A211050 A211051 * A211053 A211054 A211055

Keyword

nonn

Author

R. H. Hardin Mar 30 2012

Status

approved