A251094 Number of (n+1) X (2+1) 0..1 arrays with no 2 X 2 subblock having its minimum diagonal element less than its minimum antidiagonal element.

41, 212, 1109, 5817, 30517, 160086, 839758, 4405079, 23107524, 121214121, 635847599, 3335437865, 17496560104, 91780937840, 481451239589, 2525527648328, 13248049600905, 69494712657097, 364545365754237, 1912279634115658

Offset

1,1

Links

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

Formula

Empirical: a(n) = 7*a(n-1) - 11*a(n-2) + 10*a(n-3) - 3*a(n-4).

Empirical g.f.: x*(41 - 75*x + 76*x^2 - 24*x^3) / (1 - 7*x + 11*x^2 - 10*x^3 + 3*x^4). - Colin Barker, Nov 25 2018

Example

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

Crossrefs

Column 2 of A251100.

Sequence in context: A297598 A204620 A172085 * A300464 A326228 A142392

Adjacent sequences: A251091 A251092 A251093 * A251095 A251096 A251097

Keyword

nonn

Author

R. H. Hardin, Nov 29 2014

Status

approved