A250770 Number of (2+1) X (n+1) 0..1 arrays with nondecreasing x(i,j)-x(i,j-1) in the i direction and nondecreasing absolute value of x(i,j)-x(i-1,j) in the j direction.

18, 34, 62, 114, 214, 410, 798, 1570, 3110, 6186, 12334, 24626, 49206, 98362, 196670, 393282, 786502, 1572938, 3145806, 6291538, 12582998, 25165914, 50331742, 100663394, 201326694, 402653290, 805306478, 1610612850, 3221225590

Offset

1,1

Links

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

Formula

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

Empirical g.f.: 2*x*(9 - 19*x + 8*x^2) / ((1 - x)^2*(1 - 2*x)). - Colin Barker, Nov 19 2018

Example

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

Crossrefs

Row 2 of A250769.

Sequence in context: A357439 A044063 A044444 * A014640 A245587 A215137

Adjacent sequences: A250767 A250768 A250769 * A250771 A250772 A250773

Keyword

nonn

Author

R. H. Hardin, Nov 27 2014

Status

approved