A253436 Number of (2+1) X (n+1) 0..1 arrays with every 2 X 2 subblock diagonal minus antidiagonal sum nondecreasing horizontally, vertically and ne-to-sw antidiagonally.

39, 58, 70, 102, 174, 318, 606, 1182, 2334, 4638, 9246, 18462, 36894, 73758, 147486, 294942, 589854, 1179678, 2359326, 4718622, 9437214, 18874398, 37748766, 75497502, 150994974, 301989918, 603979806, 1207959582, 2415919134, 4831838238

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) + 30 for n>3.

Empirical g.f.: x*(39 - 59*x - 26*x^2 + 8*x^3 + 8*x^4) / ((1 - x)*(1 - 2*x)). - Colin Barker, Dec 12 2018

Example

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

Crossrefs

Row 2 of A253435.

Sequence in context: A156333 A116281 A168530 * A253429 A338794 A050780

Adjacent sequences: A253433 A253434 A253435 * A253437 A253438 A253439

Keyword

nonn

Author

R. H. Hardin, Dec 31 2014

Status

approved