A229418 Number of 4X4 0..n zero-diagonal arrays with corresponding row and column sums equal.

152, 4743, 59008, 426425, 2164680, 8583967, 28371968, 81545697, 209841400, 493679879, 1078445952, 2213497273, 4308069416, 8009070975, 14306664448, 24674505857, 41252568408, 67081603015, 106399491200, 165011023737

Offset: 1

Author

R. H. Hardin Sep 22 2013

Keywords

• nonn

Comments

Row 4 of A229417

Examples

			Some solutions for n=4
..0..1..1..4....0..1..1..4....0..0..2..4....0..0..1..3....0..1..2..3
..0..0..1..2....4..0..1..3....0..0..3..1....1..0..2..2....2..0..3..2
..2..0..0..1....2..3..0..0....4..0..0..1....0..3..0..2....1..4..0..3
..4..2..1..0....0..4..3..0....2..4..0..0....3..2..2..0....3..2..3..0
		

Formula

Empirical: a(n) = (29/140)*n^9 + (261/140)*n^8 + (811/105)*n^7 + (289/15)*n^6 + (1921/60)*n^5 + (2221/60)*n^4 + (6323/210)*n^3 + (3539/210)*n^2 + (208/35)*n + 1