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A201974
Number of n X n 0..3 arrays with rows and columns lexicographically nondecreasing read forwards and nonincreasing read backwards.
0
4, 30, 1372, 408599, 858105364, 13486744809160, 1716349328902123738
OFFSET
1,1
COMMENTS
Diagonal of A201981.
EXAMPLE
Some solutions for n=3
..0..3..3....0..0..2....2..3..3....0..2..2....1..2..2....0..2..3....0..1..2
..0..3..3....2..3..0....3..1..2....1..0..2....3..0..2....1..0..3....2..1..1
..3..2..2....3..2..0....3..3..0....3..3..0....3..2..0....2..1..0....3..2..0
CROSSREFS
Cf. A201981.
Sequence in context: A337969 A234566 A365366 * A221250 A119926 A103307
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 07 2011
STATUS
approved