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A211092 1/4 the number of n X n 0..3 symmetric matrices with every element equal to two or three horizontal and vertical neighbors 0
0, 1, 1, 19, 136, 3496, 100204, 6012109, 537556135, 86449986124, 22576823498161, 10130717811503530, 7577956550025798379 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

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

EXAMPLE

Some solutions for n=4

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

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

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

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

CROSSREFS

Sequence in context: A215863 A101090 A213122 * A142746 A221226 A139902

Adjacent sequences:  A211089 A211090 A211091 * A211093 A211094 A211095

KEYWORD

nonn

AUTHOR

R. H. Hardin Mar 31 2012

STATUS

approved

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Last modified October 23 17:19 EDT 2019. Contains 328373 sequences. (Running on oeis4.)