A251484 Number of (n+1) X (1+1) 0..3 arrays with no 2 X 2 subblock having the sum of its diagonal elements less than the minimum of its antidiagonal elements.

236, 3456, 50576, 740096, 10830016, 158478336, 2319053056, 33935282176, 496583453696, 7266629615616, 106334404775936, 1556017884102656, 22769598050123776, 333193211119927296, 4875699416916361216

Offset

1,1

Links

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

Formula

Empirical: a(n) = 16*a(n-1) - 20*a(n-2).

Empirical g.f.: 4*x*(59 - 80*x) / (1 - 16*x + 20*x^2). - Colin Barker, Nov 29 2018

Example

Some solutions for n=3:
..0..1....2..1....1..1....1..3....2..2....2..0....1..3....0..0....1..3....0..2
..3..2....2..0....2..1....2..2....3..1....1..2....1..1....0..1....1..1....1..1
..0..2....2..0....1..3....1..1....0..0....0..0....0..3....1..3....1..3....0..1
..0..1....1..1....3..3....0..0....2..2....2..0....0..3....0..0....1..1....3..2

Crossrefs

Column 1 of A251491.

Sequence in context: A334649 A233983 A251491 * A247475 A233166 A138820

Adjacent sequences: A251481 A251482 A251483 * A251485 A251486 A251487

Keyword

nonn

Author

R. H. Hardin, Dec 03 2014

Status

approved