A250975 Number of (n+1) X (1+1) 0..2 arrays with no 2 X 2 subblock having the sum of its diagonal elements less than the absolute difference of its antidiagonal elements.

71, 562, 4459, 35381, 280728, 2227408, 17673153, 140225934, 1112609193, 8827890666, 70044049696, 555757777662, 4409606651432, 34987599997513, 277605748165393, 2202636117365747, 17476604492474532, 138666437991429781

Offset

1,1

Links

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

Formula

Empirical: a(n) = 9*a(n-1) - 10*a(n-2) + 13*a(n-3) - 6*a(n-4) + a(n-5).

Empirical g.f.: x*(71 - 77*x + 111*x^2 - 53*x^3 + 9*x^4) / (1 - 9*x + 10*x^2 - 13*x^3 + 6*x^4 - x^5). - Colin Barker, Nov 24 2018

Example

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

Crossrefs

Column 1 of A250982.

Sequence in context: A142432 A341426 A250982 * A209960 A209953 A251390

Adjacent sequences: A250972 A250973 A250974 * A250976 A250977 A250978

Keyword

nonn

Author

R. H. Hardin, Nov 29 2014

Status

approved