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A192843
Number of n X n symmetric 0..4 arrays with each element equal to at least two horizontal or vertical neighbors, containing at least one 4 and with new values 0..4 introduced in lower triangular row major order
0
0, 0, 0, 0, 0, 21, 1640, 407889, 76204819, 26261341398, 12631545191076
OFFSET
1,6
EXAMPLE
Some solutions for 6X6
..0..0..1..1..3..3....0..0..1..1..3..3....0..0..1..1..3..3....0..0..0..0..2..2
..0..0..1..1..3..3....0..0..1..1..3..3....0..0..1..1..3..3....0..0..0..0..2..2
..1..1..2..2..4..4....1..1..2..2..4..4....1..1..2..2..3..3....0..0..1..1..3..3
..1..1..2..2..4..4....1..1..2..2..4..4....1..1..2..2..3..3....0..0..1..1..3..3
..3..3..4..4..3..3....3..3..4..4..1..1....3..3..3..3..4..4....2..2..3..3..4..4
..3..3..4..4..3..3....3..3..4..4..1..1....3..3..3..3..4..4....2..2..3..3..4..4
CROSSREFS
Sequence in context: A295414 A202800 A203361 * A130039 A221033 A221497
KEYWORD
nonn
AUTHOR
R. H. Hardin Jul 11 2011
STATUS
approved