A211089 - OEIS

The OEIS is supported by the many generous donors to the OEIS Foundation.

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

Other ways to Give

A211089

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

0

0, 1, 6, 348, 28140, 8126604, 5661794106, 11445238420311, 62094025253816664, 936614735379619968930, 38691771579576015771775929

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,3

LINKS

Table of n, a(n) for n=1..11.

EXAMPLE

Some solutions for n=4

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

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

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

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

CROSSREFS

Sequence in context: A047941 A229501 A289738 * A221923 A000409 A214445

Adjacent sequences: A211086 A211087 A211088 * A211090 A211091 A211092

KEYWORD

nonn

AUTHOR

R. H. Hardin Mar 31 2012

STATUS

approved