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A210899 Number of n X n 0..2 symmetric matrices with every element equal to one or two horizontal and vertical neighbors, and new values 0..2 introduced in lower triangle row major order 0
0, 1, 2, 36, 1044, 74379, 10881920, 3566285692, 2524146683822, 3922290803244487, 13291420623117002040, 98512903545177272401383 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

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

EXAMPLE

Some solutions for n=4

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

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

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

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

CROSSREFS

Sequence in context: A009554 A209036 A305596 * A302903 A259467 A003092

Adjacent sequences:  A210896 A210897 A210898 * A210900 A210901 A210902

KEYWORD

nonn

AUTHOR

R. H. Hardin Mar 29 2012

STATUS

approved

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Last modified December 2 14:09 EST 2021. Contains 349445 sequences. (Running on oeis4.)