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A265086
Number of n X 2 arrays containing 2 copies of 0..n-1 with row sums equal and column sums equal.
0
1, 2, 6, 24, 120, 720, 6300, 45360, 589680, 5443200, 94802400, 1032847200, 22962139200, 291502411200, 7764316560000, 113767670016000, 3504076928352000, 58171567341888000, 2032803670113216000
OFFSET
1,2
COMMENTS
Column 2 of A265089.
EXAMPLE
Some solutions for n=5
..0..4....1..3....2..2....4..0....0..4....2..2....1..3....1..3....3..1....3..1
..2..2....2..2....0..4....1..3....3..1....0..4....0..4....4..0....0..4....0..4
..1..3....3..1....4..0....2..2....4..0....1..3....4..0....0..4....4..0....2..2
..4..0....4..0....3..1....3..1....2..2....4..0....2..2....2..2....2..2....4..0
..3..1....0..4....1..3....0..4....1..3....3..1....3..1....3..1....1..3....1..3
CROSSREFS
Cf. A265089.
Sequence in context: A350113 A129655 A114796 * A114790 A352430 A292749
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 01 2015
STATUS
approved