A251084 Number of (n+1) X (4+1) 0..2 arrays with no 2 X 2 subblock having the sum of its diagonal elements greater than the absolute difference of its antidiagonal elements.

420, 1306, 2362, 4718, 8512, 15780, 28616, 52934, 98550, 186788, 358250, 695798, 1363076, 2688996, 5329268, 10596902, 21115770, 42135172, 84151526, 168159190, 336144664, 672082436, 1343919232, 2687549958, 5374762142, 10749132260

Offset

1,1

Links

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

Formula

Empirical: a(n) = 6*a(n-1) - 13*a(n-2) + 10*a(n-3) + 5*a(n-4) - 14*a(n-5) + 9*a(n-6) - 2*a(n-7) for n>8.

Empirical g.f.: 2*x*(210 - 607*x - 7*x^2 + 1662*x^3 - 2125*x^4 + 886*x^5 + 53*x^6 - 89*x^7) / ((1 - x)^5*(1 + x)*(1 - 2*x)). - Colin Barker, Nov 24 2018

Example

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

Crossrefs

Column 4 of A251088.

Sequence in context: A259025 A281210 A235233 * A250383 A145678 A160372

Adjacent sequences: A251081 A251082 A251083 * A251085 A251086 A251087

Keyword

nonn

Author

R. H. Hardin, Nov 29 2014

Status

approved