A258559 Number of (6+1) X (n+1) 0..1 arrays with every 2 X 2 subblock ne-sw antidiagonal difference nondecreasing horizontally and nw+se diagonal sum nondecreasing vertically.

988, 2530, 3980, 6196, 8339, 10854, 13833, 17058, 20414, 23858, 27446, 31237, 35188, 39256, 43497, 47970, 52632, 57440, 62450, 67721, 73210, 78874, 84769, 90954, 97386, 104022, 110918, 118133, 125624, 133348, 141361, 149722, 158388, 167316, 176562

Offset

1,1

Links

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

Formula

Empirical: a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) + a(n-4) - 3*a(n-5) + 3*a(n-6) - a(n-7) for n>13.

Empirical g.f.: x*(988 - 434*x - 646*x^2 + 858*x^3 - 1827*x^4 + 879*x^5 + 738*x^6 - 1076*x^7 + 724*x^8 - 488*x^9 - 36*x^10 + 277*x^11 + 72*x^12) / ((1 - x)^4*(1 + x)*(1 + x^2)). - Colin Barker, Dec 22 2018

Example

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

Crossrefs

Row 6 of A258554.

Sequence in context: A045733 A250490 A258552 * A235762 A235545 A232429

Adjacent sequences: A258556 A258557 A258558 * A258560 A258561 A258562

Keyword

nonn

Author

R. H. Hardin, Jun 03 2015

Status

approved