A251222 Number of (n+1) X (2+1) 0..1 arrays with no 2 X 2 subblock having the minimum of its diagonal elements greater than the absolute difference of its antidiagonal elements.

49, 305, 1892, 11753, 72985, 453273, 2814985, 17482154, 108570830, 674266427, 4187452312, 26005680486, 161505221644, 1003009195172, 6229070707553, 38684911434209, 240248095245952, 1492032555580773, 9266092805568853

Offset: 1

Author

R. H. Hardin, Nov 30 2014

Keywords

• nonn

Examples

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

Links

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

Crossrefs

Column 2 of A251228.

Formula

Empirical: a(n) = 5*a(n-1) + 9*a(n-2) - 8*a(n-3) - 8*a(n-4) + 3*a(n-5).

Empirical g.f.: x*(49 + 60*x - 74*x^2 - 60*x^3 + 24*x^4) / ((1 - x)*(1 + x)*(1 - 5*x - 8*x^2 + 3*x^3)). - Colin Barker, Nov 27 2018