A250736 Number of (7+1)X(n+1) 0..1 arrays with nondecreasing x(i,j)+x(i,j-1) in the i direction and nondecreasing min(x(i,j),x(i-1,j)) in the j direction.

275, 513, 1418, 3807, 9728, 23941, 57397, 135645, 317769, 741367, 1725118, 4010707, 9318138, 21648961, 50290988, 116846565, 271483896, 630867956, 1466032586, 3407186212, 7918751613, 18405536442, 42780485640, 99440346555, 231144060876

Offset: 1

Author

R. H. Hardin, Nov 27 2014

Keywords

• nonn

Comments

Row 7 of A250729

Examples

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

Links

• R. H. Hardin, Table of n, a(n) for n = 1..210

Formula

Empirical: a(n) = 7*a(n-1) -13*a(n-2) -18*a(n-3) +95*a(n-4) -89*a(n-5) -102*a(n-6) +264*a(n-7) -143*a(n-8) -94*a(n-9) +150*a(n-10) -60*a(n-11) -a(n-12) +6*a(n-13) -a(n-14) for n>19