A253440 Number of (6+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.

325, 324, 337, 372, 444, 588, 876, 1452, 2604, 4908, 9516, 18732, 37164, 74028, 147756, 295212, 590124, 1179948, 2359596, 4718892, 9437484, 18874668, 37749036, 75497772, 150995244, 301990188, 603980076, 1207959852, 2415919404, 4831838508

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) + 300 for n>3.

Empirical g.f.: x*(325 - 651*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..1..0..0..0....1..1..1..1..1....0..1..0..0..0....1..1..1..1..0
..1..1..0..0..0....1..1..1..1..1....0..1..0..0..0....1..1..1..1..0
..1..1..0..0..0....1..1..1..1..1....0..1..0..0..0....1..1..1..1..0
..1..1..0..0..0....1..1..1..1..1....0..1..0..0..0....1..1..1..1..0
..1..1..0..0..0....1..1..1..1..1....0..1..0..0..0....1..1..1..1..0
..1..1..0..0..0....1..1..1..1..1....0..1..0..0..0....1..1..1..1..0
..1..1..0..0..1....1..1..1..1..1....0..1..0..0..1....0..0..0..0..0

Crossrefs

Row 6 of A253435.

Sequence in context: A343080 A159976 A253433 * A253157 A184036 A159844

Adjacent sequences: A253437 A253438 A253439 * A253441 A253442 A253443

Keyword

nonn

Author

R. H. Hardin, Dec 31 2014

Status

approved