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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
OFFSET
1,3
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: A209036 A375839 A305596 * A302903 A259467 A003092
KEYWORD
nonn
AUTHOR
R. H. Hardin Mar 29 2012
STATUS
approved