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A211041 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, 0, 6, 8, 118, 880, 14400, 318220, 10446298, 531060152, 39577654480, 4465022457276, 757302604610482, 191605833481050984 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

Table of n, a(n) for n=1..15.

EXAMPLE

Some solutions for n=4

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

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

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

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

CROSSREFS

Sequence in context: A013234 A013240 A161801 * A236754 A069660 A119001

Adjacent sequences:  A211038 A211039 A211040 * A211042 A211043 A211044

KEYWORD

nonn

AUTHOR

R. H. Hardin Mar 30 2012

STATUS

approved

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Last modified August 7 23:38 EDT 2020. Contains 336279 sequences. (Running on oeis4.)