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A251310 Number of (n+1) X (1+1) 0..1 arrays with no 2 X 2 subblock having the maximum of its diagonal elements greater than the absolute difference of its antidiagonal elements. 1
10, 25, 61, 149, 365, 894, 2189, 5360, 13125, 32139, 78698, 192706, 471875, 1155470, 2829374, 6928226, 16964995, 41541811, 101722521, 249085705, 609930700, 1493523921, 3657159252, 8955205609, 21928415465, 53695629760, 131483310316 (list; graph; refs; listen; history; text; internal format)
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) + 2*a(n-3) - a(n-4).

Empirical g.f.: x*(10 - 5*x + 6*x^2 - 4*x^3) / (1 - 3*x + 2*x^2 - 2*x^3 + x^4). - Colin Barker, Nov 28 2018

EXAMPLE

Some solutions for n=4:

..1..1....1..1....1..0....0..0....1..0....0..1....0..1....0..1....1..0....0..1

..0..1....0..0....1..0....0..0....1..0....0..1....0..0....0..1....1..0....0..0

..0..1....0..0....1..1....1..1....1..1....0..0....1..1....0..0....1..0....1..1

..1..0....1..0....0..0....0..1....0..1....1..1....0..1....1..0....1..1....0..1

..1..1....1..1....1..0....0..1....0..0....0..0....1..0....1..0....0..0....0..0

CROSSREFS

Column 1 of A251317.

Sequence in context: A263310 A063424 A137930 * A251194 A071289 A268303

Adjacent sequences:  A251307 A251308 A251309 * A251311 A251312 A251313

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 01 2014

STATUS

approved

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Last modified October 19 21:48 EDT 2021. Contains 348095 sequences. (Running on oeis4.)