A251094 Number of (n+1) X (2+1) 0..1 arrays with no 2 X 2 subblock having its minimum diagonal element less than its minimum antidiagonal element.

41, 212, 1109, 5817, 30517, 160086, 839758, 4405079, 23107524, 121214121, 635847599, 3335437865, 17496560104, 91780937840, 481451239589, 2525527648328, 13248049600905, 69494712657097, 364545365754237, 1912279634115658

Offset: 1

Author

R. H. Hardin, Nov 29 2014

Keywords

• nonn

Examples

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

Links

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

Crossrefs

Column 2 of A251100.

Formula

Empirical: a(n) = 7*a(n-1) - 11*a(n-2) + 10*a(n-3) - 3*a(n-4).

Empirical g.f.: x*(41 - 75*x + 76*x^2 - 24*x^3) / (1 - 7*x + 11*x^2 - 10*x^3 + 3*x^4). - Colin Barker, Nov 25 2018