A253153 Number of (n+1) X (2+1) 0..1 arrays with every 2 X 2 subblock diagonal minus antidiagonal sum nondecreasing horizontally and vertically.

39, 72, 88, 120, 192, 336, 624, 1200, 2352, 4656, 9264, 18480, 36912, 73776, 147504, 294960, 589872, 1179696, 2359344, 4718640, 9437232, 18874416, 37748784, 75497520, 150994992, 301989936, 603979824, 1207959600, 2415919152, 4831838256

Offset

1,1

Links

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

Formula

Empirical: a(n) = 3*a(n-1) -2*a(n-2) for n>5.

Empirical: a(n) = 9*2^(n-1) + 48 for n>3.

Empirical g.f.: x*(39 - 45*x - 50*x^2 + 8*x^4) / ((1 - x)*(1 - 2*x)). - Colin Barker, Dec 09 2018

Example

Some solutions for n=6:
..0..1..1....1..1..1....0..1..1....0..0..0....0..0..0....0..1..1....1..1..1
..1..1..1....1..1..1....1..1..1....1..1..1....1..1..1....0..0..0....0..0..0
..1..1..1....0..0..0....1..0..0....1..1..1....1..1..1....1..1..1....1..1..1
..0..0..0....1..1..1....1..0..0....0..0..0....0..0..0....1..1..1....0..0..0
..0..0..0....1..1..1....1..0..0....1..1..1....1..1..1....0..0..0....1..1..1
..1..1..1....0..0..0....1..0..0....0..0..0....1..1..1....1..1..1....0..0..0
..1..1..1....0..0..0....0..0..1....0..0..0....1..1..1....0..0..1....0..0..0

Crossrefs

Column 2 of A253159.

Sequence in context: A039467 A250657 A243577 * A044105 A044486 A072122

Adjacent sequences: A253150 A253151 A253152 * A253154 A253155 A253156

Keyword

nonn

Author

R. H. Hardin, Dec 28 2014

Status

approved