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A211050
1/3 the number of n X n 0..2 symmetric matrices with every element equal to two or three horizontal and vertical neighbors
0
0, 1, 1, 11, 69, 1059, 21565, 767763, 42018069, 3765457981, 536609175439, 123351155903565, 45453341030199701, 26933811670713434089
OFFSET
1,4
EXAMPLE
Some solutions for n=4
..0..0..0..0....2..2..0..0....2..2..2..2....0..0..1..1....0..0..0..0
..0..0..0..0....2..2..0..0....2..1..1..2....0..0..1..1....0..0..0..0
..0..0..2..2....0..0..0..0....2..1..1..2....1..1..1..1....0..0..1..1
..0..0..2..2....0..0..0..0....2..2..2..2....1..1..1..1....0..0..1..1
CROSSREFS
Sequence in context: A182188 A099336 A236320 * A295074 A173200 A071746
KEYWORD
nonn
AUTHOR
R. H. Hardin Mar 30 2012
STATUS
approved