A253428 Number of (n+1)X(n+1) 0..1 arrays with every 2X2 subblock diagonal minus antidiagonal sum nondecreasing horizontally, vertically and ne-to-sw antidiagonally

16, 58, 85, 156, 300, 588, 1164, 2316, 4620, 9228, 18444, 36876, 73740, 147468, 294924, 589836, 1179660, 2359308, 4718604, 9437196, 18874380, 37748748, 75497484, 150994956, 301989900, 603979788

Offset

1,1

Comments

Diagonal of A253435

Links

Table of n, a(n) for n=1..26.

Formula

Empirical: a(n) = 3*a(n-1) -2*a(n-2) for n>5

Empirical: a(n) = 9*2^n + 12 for n>3

Example

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

Crossrefs

Sequence in context: A235449 A235736 A235517 * A005905 A177890 A225922

Adjacent sequences: A253425 A253426 A253427 * A253429 A253430 A253431

Keyword

nonn

Author

R. H. Hardin, Dec 31 2014

Status

approved