A251083 Number of (n+1) X (3+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.

192, 616, 1165, 2362, 4379, 8284, 15411, 29142, 55429, 106880, 207889, 407938, 805159, 1596500, 3175015, 6327486, 12626625, 25218520, 50394485, 100737802, 201414163, 402755596, 805425275, 1610750182, 3221383389, 6442631664

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.: x*(192 - 536*x - 35*x^2 + 1460*x^3 - 1768*x^4 + 674*x^5 + 85*x^6 - 82*x^7) / ((1 - x)^5*(1 + x)*(1 - 2*x)). - Colin Barker, Nov 24 2018

Example

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

Crossrefs

Column 3 of A251088.

Sequence in context: A232940 A254854 A254847 * A336944 A194647 A054001

Adjacent sequences: A251080 A251081 A251082 * A251084 A251085 A251086

Keyword

nonn

Author

R. H. Hardin, Nov 29 2014

Status

approved