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A211086 1/4 the number of n X n 0..3 symmetric matrices with every element equal to zero, one, two or three horizontal and vertical neighbors 1
1, 16, 960, 229824, 219386880, 834532651008, 12650446296013824, 764188858823853957120, 183961835921396390619045888, 176476517080094726836047543951360 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

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

EXAMPLE

Some solutions for n=4

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

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

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

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

CROSSREFS

Sequence in context: A211081 A197449 A264640 * A187802 A181199 A024301

Adjacent sequences:  A211083 A211084 A211085 * A211087 A211088 A211089

KEYWORD

nonn

AUTHOR

R. H. Hardin Mar 31 2012

STATUS

approved

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Last modified September 19 04:50 EDT 2020. Contains 337175 sequences. (Running on oeis4.)