A258549 Number of (n+1) X (3+1) 0..1 arrays with every 2 X 2 subblock ne-sw antidiagonal difference nondecreasing horizontally and nw+se diagonal sum nondecreasing vertically.

104, 210, 598, 1244, 2384, 3980, 6348, 9567, 13847, 19227, 26071, 34506, 44790, 57010, 71578, 88669, 108589, 131473, 157781, 187736, 221692, 259832, 302664, 350459, 403619, 462375, 527283, 598662, 676962, 762462, 855766, 957241, 1067385

Offset

1,1

Links

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

Formula

Empirical: a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - 4*a(n-5) + 6*a(n-6) - 4*a(n-7) + a(n-8) for n>11.

Empirical g.f.: x*(104 - 206*x + 382*x^2 - 304*x^3 + 156*x^4 - 68*x^5 - 28*x^6 + 67*x^7 - 129*x^8 + 103*x^9 - 29*x^10) / ((1 - x)^5*(1 + x)*(1 + x^2)). - Colin Barker, Dec 21 2018

Example

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

Crossrefs

Column 3 of A258554.

Sequence in context: A235990 A270300 A108665 * A121962 A235011 A271745

Adjacent sequences: A258546 A258547 A258548 * A258550 A258551 A258552

Keyword

nonn

Author

R. H. Hardin, Jun 03 2015

Status

approved