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A211085 1/4 the number of n X n 0..3 symmetric matrices with every element equal to one, two or three horizontal and vertical neighbors 0
0, 1, 12, 504, 54552, 18314238, 18001425828, 52877461613730, 461270181887973636, 11975672062199372507844, 924700036496758370728369296 (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

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

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

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

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

CROSSREFS

Sequence in context: A279302 A227052 A176731 * A197600 A197984 A197771

Adjacent sequences:  A211082 A211083 A211084 * A211086 A211087 A211088

KEYWORD

nonn

AUTHOR

R. H. Hardin Mar 31 2012

STATUS

approved

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Last modified October 31 19:00 EDT 2020. Contains 338111 sequences. (Running on oeis4.)