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A211083 1/4 the number of n X n 0..3 symmetric matrices with every element equal to two or three horizontal and vertical neighbors 0
0, 1, 0, 12, 18, 624, 6012, 228984, 8210664, 619049280, 63783422784, 11382530540616 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

Table of n, a(n) for n=1..12.

EXAMPLE

Some solutions for n=6

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

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

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

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

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

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

CROSSREFS

Sequence in context: A212128 A110932 A112880 * A100541 A337424 A056688

Adjacent sequences:  A211080 A211081 A211082 * A211084 A211085 A211086

KEYWORD

nonn

AUTHOR

R. H. Hardin Mar 31 2012

STATUS

approved

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Last modified October 28 13:09 EDT 2021. Contains 348329 sequences. (Running on oeis4.)