A251222 Number of (n+1) X (2+1) 0..1 arrays with no 2 X 2 subblock having the minimum of its diagonal elements greater than the absolute difference of its antidiagonal elements.

49, 305, 1892, 11753, 72985, 453273, 2814985, 17482154, 108570830, 674266427, 4187452312, 26005680486, 161505221644, 1003009195172, 6229070707553, 38684911434209, 240248095245952, 1492032555580773, 9266092805568853

Offset

1,1

Links

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

Formula

Empirical: a(n) = 5*a(n-1) + 9*a(n-2) - 8*a(n-3) - 8*a(n-4) + 3*a(n-5).

Empirical g.f.: x*(49 + 60*x - 74*x^2 - 60*x^3 + 24*x^4) / ((1 - x)*(1 + x)*(1 - 5*x - 8*x^2 + 3*x^3)). - Colin Barker, Nov 27 2018

Example

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

Crossrefs

Column 2 of A251228.

Sequence in context: A017354 A239607 A227079 * A250967 A245033 A340124

Adjacent sequences: A251219 A251220 A251221 * A251223 A251224 A251225

Keyword

nonn

Author

R. H. Hardin, Nov 30 2014

Status

approved