A253742 Number of (n+1) X (1+1) 0..2 arrays with every 2 X 2 subblock ne-sw antidiagonal difference nondecreasing horizontally and nw+se diagonal sum nondecreasing vertically.

81, 450, 1998, 7803, 28107, 95940, 315576, 1011357, 3181653, 9876870, 30368034, 92726271, 281717919, 852821640, 2574980172, 7760330145, 23356488105, 70229896650, 211029428790, 633805512579, 1902926487411, 5711950356300

Offset

1,1

Links

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

Formula

Empirical: a(n) = 9*a(n-1) - 31*a(n-2) + 51*a(n-3) - 40*a(n-4) + 12*a(n-5).

Empirical g.f.: 9*x*(9 - 31*x + 51*x^2 - 40*x^3 + 12*x^4) / ((1 - x)^2*(1 - 2*x)^2*(1 - 3*x)). - Colin Barker, Dec 17 2018

Example

Some solutions for n=4:
..2..0....0..1....1..0....0..2....0..1....0..1....1..1....2..0....0..1....1..2
..1..0....0..2....1..0....1..0....0..0....0..1....0..0....2..1....0..0....2..1
..2..1....0..2....1..0....2..1....1..1....1..1....2..1....2..1....2..2....1..0
..2..1....2..2....2..1....0..0....1..1....2..1....2..1....2..2....2..0....2..1
..2..1....1..1....2..0....1..2....2..2....0..1....2..1....0..2....2..2....1..1

Crossrefs

Column 1 of A253749.

Sequence in context: A204230 A235441 A235406 * A204223 A205215 A206223

Adjacent sequences: A253739 A253740 A253741 * A253743 A253744 A253745

Keyword

nonn

Author

R. H. Hardin, Jan 11 2015

Status

approved