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A210930
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, 64, 4730, 1354791, 943637970, 1907539841676, 10349004212065264, 156102455896727660205
OFFSET
1,3
EXAMPLE
Some solutions for n=4
..0..0..1..1....0..0..2..2....0..0..0..2....0..0..1..1....0..0..0..0
..0..0..2..0....0..1..1..1....0..1..1..2....0..0..1..0....0..1..1..0
..1..2..2..0....2..1..2..2....0..1..1..3....1..1..1..0....0..1..1..1
..1..0..0..0....2..1..2..2....2..2..3..3....1..0..0..0....0..0..1..1
CROSSREFS
Sequence in context: A187548 A300640 A054956 * A263185 A155957 A085535
KEYWORD
nonn
AUTHOR
R. H. Hardin Mar 29 2012
STATUS
approved