A253526 Number of (n+1) X (1+1) 0..2 arrays with every 2 X 2 subblock antidiagonal maximum minus diagonal minimum nondecreasing horizontally and diagonal maximum minus antidiagonal minimum nondecreasing vertically.

81, 459, 1963, 7253, 25165, 85663, 291511, 997121, 3427953, 11826315, 40885971, 141512469, 490082653, 1697732055, 5882051383, 20380576545, 70618256025, 244694019755, 847876017411, 2937937280013, 10180127318973, 35274764991959

Offset

1,1

Links

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

Formula

Empirical: a(n) = 8*a(n-1) - 22*a(n-2) + 21*a(n-3) + 13*a(n-4) - 46*a(n-5) + 40*a(n-6) - 15*a(n-7) + 2*a(n-8).

Empirical g.f.: x*(81 - 189*x + 73*x^2 - 54*x^3 - 365*x^4 + 445*x^5 - 121*x^6 + 18*x^7) / ((1 - x)^4*(1 - 4*x + 7*x^3 - 2*x^4)). - Colin Barker, Dec 17 2018

Example

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

Crossrefs

Column 1 of A253533.

Sequence in context: A236664 A253533 A183971 * A183963 A236354 A236349

Adjacent sequences: A253523 A253524 A253525 * A253527 A253528 A253529

Keyword

nonn

Author

R. H. Hardin, Jan 03 2015

Status

approved