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A198278
Number of 2nX2n 0..2 arrays with values 0..2 introduced in row major order and each element equal to exactly two horizontal and vertical neighbors
0
1, 4, 100, 8784, 2823604, 3337609528
OFFSET
1,2
COMMENTS
Diagonal of A198285
EXAMPLE
Some solutions for n=3
..0..0..1..1..2..2....0..0..1..1..1..1....0..0..1..1..0..0....0..0..1..1..0..0
..0..0..1..1..2..2....0..0..1..0..0..1....0..0..1..1..0..0....0..0..1..1..0..0
..1..1..2..2..0..0....2..2..1..0..0..1....1..1..0..0..2..2....1..1..0..0..1..1
..1..1..2..2..0..0....2..2..1..2..2..1....1..1..0..0..2..2....1..1..0..0..1..1
..2..2..1..1..2..2....0..0..1..2..2..1....2..2..1..1..0..0....0..0..1..1..0..0
..2..2..1..1..2..2....0..0..1..1..1..1....2..2..1..1..0..0....0..0..1..1..0..0
CROSSREFS
Sequence in context: A224385 A249939 A224018 * A202990 A324096 A202989
KEYWORD
nonn
AUTHOR
R. H. Hardin Oct 23 2011
STATUS
approved