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A211050 1/3 the number of n X n 0..2 symmetric matrices with every element equal to two or three horizontal and vertical neighbors 0
0, 1, 1, 11, 69, 1059, 21565, 767763, 42018069, 3765457981, 536609175439, 123351155903565, 45453341030199701, 26933811670713434089 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

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

EXAMPLE

Some solutions for n=4

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

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

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

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

CROSSREFS

Sequence in context: A182188 A099336 A236320 * A295074 A173200 A071746

Adjacent sequences:  A211047 A211048 A211049 * A211051 A211052 A211053

KEYWORD

nonn

AUTHOR

R. H. Hardin Mar 30 2012

STATUS

approved

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Last modified August 3 20:08 EDT 2020. Contains 336201 sequences. (Running on oeis4.)