A250834 Number of (n+1) X (1+1) 0..2 arrays with no 2 X 2 subblock having a diagonal absolute difference less than its antidiagonal absolute difference.

55, 333, 2011, 12145, 73351, 443013, 2675635, 16159849, 97599535, 589465245, 3560152987, 21502012897, 129864239095, 784332177525, 4737077497219, 28610203505305, 172795092564223, 1043618721857421, 6303072734583595

Offset

1,1

Links

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

Formula

Empirical: a(n) = 8*a(n-1) - 13*a(n-2) + 8*a(n-3) - 6*a(n-4).

Empirical g.f.: x*(55 - 107*x + 62*x^2 - 54*x^3) / (1 - 8*x + 13*x^2 - 8*x^3 + 6*x^4). - Colin Barker, Nov 21 2018

Example

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

Crossrefs

Column 1 of A250841.

Sequence in context: A330382 A140197 A250841 * A020280 A063653 A222348

Adjacent sequences: A250831 A250832 A250833 * A250835 A250836 A250837

Keyword

nonn

Author

R. H. Hardin, Nov 27 2014

Status

approved