A229867 Number of n X n 0..3 arrays with corresponding row and column sums equal.
4, 64, 8704, 15106048, 354003288064, 115737559589453824, 542277543422445827915776
Offset: 1
Keywords
Examples
Some solutions for n=4 ..0..0..2..2....0..2..0..2....0..0..2..2....0..2..0..0....0..2..2..0 ..2..1..0..2....0..0..2..0....0..2..3..2....2..3..3..0....2..1..1..0 ..1..2..1..2....3..0..2..1....3..2..1..1....0..0..1..3....2..0..3..2 ..1..2..3..2....1..0..2..0....1..3..1..0....0..3..0..0....0..1..1..1
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