A253438 Number of (4+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.

109, 108, 121, 156, 228, 372, 660, 1236, 2388, 4692, 9300, 18516, 36948, 73812, 147540, 294996, 589908, 1179732, 2359380, 4718676, 9437268, 18874452, 37748820, 75497556, 150995028, 301989972, 603979860, 1207959636, 2415919188, 4831838292

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) + 84 for n>3.

Empirical g.f.: x*(109 - 219*x + 15*x^2 + 9*x^3 + 2*x^4) / ((1 - x)*(1 - 2*x)). - Colin Barker, Dec 12 2018

Example

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

Crossrefs

Row 4 of A253435.

Sequence in context: A247440 A130705 A253431 * A263194 A231701 A051046

Adjacent sequences: A253435 A253436 A253437 * A253439 A253440 A253441

Keyword

nonn

Author

R. H. Hardin, Dec 31 2014

Status

approved