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A210926
Number of n X n 0..3 symmetric matrices with every element equal to one, two or three horizontal and vertical neighbors, and new values 0..3 introduced in lower triangle row major order
1
0, 1, 4, 95, 9220, 3055073, 3000338892, 8812917082915, 76878364475257062, 1995945343880703817038, 154116672749530867319434810
OFFSET
1,3
EXAMPLE
Some solutions for n=4
..0..0..1..0....0..0..1..1....0..0..0..1....0..0..0..0....0..0..1..1
..0..0..1..0....0..0..1..1....0..1..1..1....0..1..1..0....0..0..1..0
..1..1..2..2....1..1..1..0....0..1..1..0....0..1..1..0....1..1..1..0
..0..0..2..2....1..1..0..0....1..1..0..0....0..0..0..0....1..0..0..0
CROSSREFS
Sequence in context: A220429 A210857 A220682 * A302121 A188895 A068114
KEYWORD
nonn
AUTHOR
R. H. Hardin Mar 29 2012
STATUS
approved