A250765 Number of (n+1) X (4+1) 0..1 arrays with nondecreasing 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.

68, 114, 196, 350, 648, 1234, 2396, 4710, 9328, 18554, 36996, 73870, 147608, 295074, 589996, 1179830, 2359488, 4718794, 9437396, 18874590, 37748968, 75497714, 150995196, 301990150, 603980048, 1207959834, 2415919396, 4831838510

Offset: 1

Author

R. H. Hardin, Nov 27 2014

Keywords

• nonn

Examples

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

Links

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

Crossrefs

Column 4 of A250769.

Formula

Empirical: a(n) = 4*a(n-1) - 5*a(n-2) + 2*a(n-3); a(n) = 36*2^(n-1) + 10*n + 22.

Empirical g.f.: 2*x*(34 - 79*x + 40*x^2) / ((1 - x)^2*(1 - 2*x)). - Colin Barker, Nov 18 2018