A251194 Number of (n+1) X (1+1) 0..1 arrays with no 2 X 2 subblock having the minimum of its diagonal elements less than the absolute difference of its antidiagonal elements.

10, 25, 64, 164, 421, 1081, 2776, 7129, 18308, 47017, 120745, 310087, 796339, 2045090, 5252026, 13487806, 34638235, 88954966, 228446570, 586677031, 1506654001, 3869260528, 9936705457, 25518600938, 65534698261, 168300632413

Offset

1,1

Links

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

Formula

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

Empirical g.f.: x*(10 + 5*x - 6*x^2 - 4*x^3) / (1 - 2*x - 2*x^2 + x^3 + x^4). - Colin Barker, Nov 26 2018

Example

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

Crossrefs

Column 1 of A251201.

Sequence in context: A063424 A137930 A251310 * A071289 A268303 A248833

Adjacent sequences: A251191 A251192 A251193 * A251195 A251196 A251197

Keyword

nonn

Author

R. H. Hardin, Nov 30 2014

Status

approved