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A210922 Number of n X n 0..3 symmetric matrices with every element equal to one or two horizontal and vertical neighbors, and new values 0..3 introduced in lower triangle row major order 0
0, 1, 2, 49, 3312, 818235, 488196032, 845278581938, 3889846475035188, 49699973559580684560 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Table of n, a(n) for n=1..10.

EXAMPLE

Some solutions for n=4

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

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

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

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

CROSSREFS

Sequence in context: A001568 A221134 A243720 * A257742 A269839 A088067

Adjacent sequences: A210919 A210920 A210921 * A210923 A210924 A210925

KEYWORD

nonn

AUTHOR

R. H. Hardin Mar 29 2012

STATUS

approved

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Last modified January 29 06:03 EST 2023. Contains 359915 sequences. (Running on oeis4.)