A251444 Number of (n+1) X (1+1) 0..2 arrays with no 2 X 2 subblock having the minimum of its diagonal elements less than the absolute difference of its antidiagonal elements.

45, 230, 1223, 6505, 34674, 184818, 985223, 5251978, 27997157, 149246726, 795601948, 4241181436, 22608818826, 120522711787, 642480449013, 3424923993155, 18257527334186, 97326920253559, 518828712819995

Offset

1,1

Links

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

Formula

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

Empirical g.f.: x*(45 + 5*x - 107*x^2 - 35*x^3 + 57*x^4 + 36*x^5) / ((1 - x)*(1 - 4*x - 8*x^2 + 3*x^3 + 9*x^4 + 4*x^5)). - Colin Barker, Nov 29 2018

Example

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

Crossrefs

Column 1 of A251451.

Sequence in context: A334035 A280059 A251451 * A169717 A246420 A172118

Adjacent sequences: A251441 A251442 A251443 * A251445 A251446 A251447

Keyword

nonn

Author

R. H. Hardin, Dec 02 2014

Status

approved