A250793 Number of (n+1) X (4+1) 0..1 arrays with nondecreasing min(x(i,j),x(i,j-1)) in the i direction and nondecreasing absolute value of x(i,j)-x(i-1,j) in the j direction.

118, 376, 1190, 3776, 12062, 38676, 124366, 400616, 1292134, 4171276, 13474406, 43546448, 140781326, 455247108, 1472416318, 4762930232, 15408574198, 49852141564, 161298304598, 521908159904, 1688775756830, 5464620624372

Offset: 1

Author

R. H. Hardin, Nov 27 2014

Keywords

• nonn

Examples

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

Links

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

Crossrefs

Column 4 of A250797.

Formula

Empirical: a(n) = 8*a(n-1) - 20*a(n-2) + 8*a(n-3) + 33*a(n-4) - 36*a(n-5) + 8*a(n-7).

Empirical g.f.: 2*x*(59 - 284*x + 271*x^2 + 416*x^3 - 624*x^4 + 10*x^5 + 128*x^6) / ((1 - x)^2*(1 - 2*x)*(1 - 2*x - x^2)*(1 - 2*x - 4*x^2)). - Colin Barker, Nov 20 2018