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A211078
1/4 the number of (2n)X(2n) 0..3 symmetric matrices with every element equal to two horizontal and vertical neighbors
0
1, 12, 408, 39072, 10448832, 7784500224, 16120594140672, 92699207728336896
OFFSET
1,2
EXAMPLE
Some solutions for n=2
..2..2..2..2....2..2..0..0....0..0..3..3....0..0..1..1....2..2..0..0
..2..1..1..2....2..2..0..0....0..0..3..3....0..0..1..1....2..2..0..0
..2..1..1..2....0..0..1..1....3..3..2..2....1..1..3..3....0..0..3..3
..2..2..2..2....0..0..1..1....3..3..2..2....1..1..3..3....0..0..3..3
CROSSREFS
Sequence in context: A285028 A292784 A003772 * A299382 A197038 A282883
KEYWORD
nonn
AUTHOR
R. H. Hardin Mar 31 2012
STATUS
approved