A237853 Number of (n+1) X (2+1) 0..1 arrays with no element greater than all horizontal neighbors or less than all vertical neighbors.

4, 14, 41, 114, 325, 943, 2731, 7876, 22702, 65489, 188972, 545229, 1572979, 4538047, 13092532, 37772848, 108976855, 314404070, 907073003, 2616956517, 7550066383, 21782363122, 62843332744, 181306523557, 523079446954, 1509113417351

Offset

1,1

Links

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

Formula

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

Empirical g.f.: x*(4 + 2*x + 7*x^2 + 3*x^3 + x^4) / (1 - 3*x + 2*x^2 - 4*x^3 - 2*x^4 - x^5). - Colin Barker, Oct 24 2018

Example

Some solutions for n=5:
..1..1..1....0..0..0....0..1..1....1..1..0....0..1..1....1..1..0....1..1..0
..0..1..1....0..0..0....0..1..1....1..1..0....0..1..1....0..0..0....1..1..0
..0..0..0....0..1..1....0..1..1....1..1..1....0..0..0....0..0..0....1..1..1
..0..0..0....1..1..0....0..1..1....1..1..1....0..0..0....1..1..1....0..0..0
..1..1..1....0..0..0....0..1..1....0..1..1....0..0..0....0..1..1....0..0..0
..1..1..1....0..0..0....0..1..1....0..1..1....1..1..0....0..1..1....0..0..0

Crossrefs

Column 2 of A237859.

Sequence in context: A196713 A375406 A358587 * A132357 A262875 A219867

Adjacent sequences: A237850 A237851 A237852 * A237854 A237855 A237856

Keyword

nonn

Author

R. H. Hardin, Feb 14 2014

Status

approved