A251003 Number of (n+1) X (1+1) 0..2 arrays with no 2 X 2 subblock having its maximum diagonal element less than the absolute difference of its antidiagonal elements.

69, 530, 4083, 31456, 242326, 1866789, 14381065, 110786519, 853459216, 6574740657, 50649420520, 390184789500, 3005842285913, 23155920197037, 178384821680265, 1374212051826542, 10586431881352371, 81554036605596548

Offset

1,1

Links

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

Formula

Empirical: a(n) = 9*a(n-1) - 12*a(n-2) + 17*a(n-3) - 12*a(n-4) + 4*a(n-5).

Empirical g.f.: x*(69 - 91*x + 141*x^2 - 104*x^3 + 36*x^4) / (1 - 9*x + 12*x^2 - 17*x^3 + 12*x^4 - 4*x^5). - Colin Barker, Nov 24 2018

Example

Some solutions for n=4:
..0..0....1..2....0..0....1..0....0..0....1..1....0..2....2..1....2..0....1..0
..1..2....2..2....0..2....0..0....0..1....2..2....2..0....0..2....0..2....0..1
..2..0....2..2....2..1....2..2....1..2....2..1....1..0....2..0....2..1....1..0
..2..1....2..0....2..1....1..2....2..2....2..1....1..1....2..0....1..2....1..1
..2..2....0..0....2..0....0..2....1..2....0..1....0..0....2..2....1..2....2..1

Crossrefs

Column 1 of A251010.

Sequence in context: A234832 A234825 A251010 * A211692 A264288 A360359

Adjacent sequences: A251000 A251001 A251002 * A251004 A251005 A251006

Keyword

nonn

Author

R. H. Hardin, Nov 29 2014

Status

approved