A251243 Number of (n+1) X (2+1) 0..2 arrays with no 2 X 2 subblock having the sum of its diagonal elements less than the minimum of its antidiagonal elements.

621, 14265, 327753, 7530633, 173028393, 3975606801, 91345992921, 2098821870081, 48223825786089, 1108020364732593, 25458559305394041, 584951560945849089, 13440207851070791625, 308810505245808515409, 7095420636859874120985

Offset: 1

Author

R. H. Hardin, Dec 01 2014

Keywords

• nonn

Examples

			Some solutions for n=2:
..1..1..2....1..0..2....2..0..0....2..2..2....2..2..0....0..1..0....1..0..0
..0..1..1....2..0..2....0..1..0....1..1..0....1..1..1....2..2..2....0..0..0
..2..2..0....2..0..1....2..2..2....2..1..2....1..1..2....1..0..1....0..2..2
		

Links

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

Crossrefs

Column 2 of A251249.

Formula

Empirical: a(n) = 27*a(n-1) - 94*a(n-2) + 36*a(n-3) - 4*a(n-4) - 36*a(n-5).

Empirical g.f.: 9*x*(69 - 278*x + 108*x^2 - 16*x^3 - 108*x^4) / (1 - 27*x + 94*x^2 - 36*x^3 + 4*x^4 + 36*x^5). - Colin Barker, Nov 27 2018