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A251311 Number of (n+1) X (2+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
25, 79, 238, 720, 2199, 6717, 20484, 62464, 190542, 581259, 1773061, 5408458, 16497878, 50325018, 153510819, 468267241, 1428396280, 4357161996, 13291031298, 40542790911, 123671208989, 377245070870, 1150743527834, 3510213300150 (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) = 5*a(n-1) - 9*a(n-2) + 13*a(n-3) - 13*a(n-4) + 6*a(n-5) - 2*a(n-6).

Empirical g.f.: x*(25 - 46*x + 68*x^2 - 84*x^3 + 39*x^4 - 15*x^5) / (1 - 5*x + 9*x^2 - 13*x^3 + 13*x^4 - 6*x^5 + 2*x^6). - Colin Barker, Nov 28 2018

EXAMPLE

Some solutions for n=4:

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

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

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

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

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

CROSSREFS

Column 2 of A251317.

Sequence in context: A033658 A080699 A134153 * A223181 A016814 A280343

Adjacent sequences:  A251308 A251309 A251310 * A251312 A251313 A251314

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 01 2014

STATUS

approved

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Last modified September 28 19:16 EDT 2021. Contains 347717 sequences. (Running on oeis4.)