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A211088 1/4 the number of n X n 0..3 symmetric matrices with every element equal to zero or two horizontal and vertical neighbors 0
1, 10, 240, 13872, 1924416, 641053824, 512493408768, 983311673066496, 4527565995515535360, 50027087182874567811072, 1326495212666507820379570176 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

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

EXAMPLE

Some solutions for n=4

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

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

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

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

CROSSREFS

Sequence in context: A221099 A171204 A156443 * A064757 A087435 A331611

Adjacent sequences:  A211085 A211086 A211087 * A211089 A211090 A211091

KEYWORD

nonn

AUTHOR

R. H. Hardin Mar 31 2012

STATUS

approved

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Last modified September 22 07:34 EDT 2020. Contains 337289 sequences. (Running on oeis4.)