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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
OFFSET
1,3
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: A221134 A243720 A369943 * A257742 A269839 A088067
KEYWORD
nonn
AUTHOR
R. H. Hardin Mar 29 2012
STATUS
approved