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A251123 Number of (n+1) X (3+1) 0..1 arrays with no 2 X 2 subblock having the sum of its diagonal elements greater than the maximum of its antidiagonal elements. 1
40, 69, 108, 173, 272, 430, 680, 1080, 1721, 2752, 4413, 7093, 11421, 18415, 29722, 48007, 77582, 125424, 202822, 328042, 530639, 858434, 1388803, 2246943, 3635427, 5882025, 9517080, 15398705, 24915356, 40313602, 65228468, 105541548, 170769461 (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) = 4*a(n-1) -5*a(n-2) +a(n-3) +2*a(n-4) -a(n-5) for n>6.

Empirical g.f.: x*(40 - 91*x + 32*x^2 + 46*x^3 - 29*x^4 + x^5) / ((1 - x)^3*(1 - x - x^2)). - Colin Barker, Nov 25 2018

EXAMPLE

Some solutions for n=4:

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

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

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

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

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

CROSSREFS

Column 3 of A251128.

Sequence in context: A043156 A039333 A043936 * A064635 A098517 A260177

Adjacent sequences:  A251120 A251121 A251122 * A251124 A251125 A251126

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 30 2014

STATUS

approved

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Last modified April 17 05:12 EDT 2021. Contains 343059 sequences. (Running on oeis4.)