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A251003 Number of (n+1) X (1+1) 0..2 arrays with no 2 X 2 subblock having its maximum diagonal element less than the absolute difference of its antidiagonal elements. 1
69, 530, 4083, 31456, 242326, 1866789, 14381065, 110786519, 853459216, 6574740657, 50649420520, 390184789500, 3005842285913, 23155920197037, 178384821680265, 1374212051826542, 10586431881352371, 81554036605596548 (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) = 9*a(n-1) - 12*a(n-2) + 17*a(n-3) - 12*a(n-4) + 4*a(n-5).

Empirical g.f.: x*(69 - 91*x + 141*x^2 - 104*x^3 + 36*x^4) / (1 - 9*x + 12*x^2 - 17*x^3 + 12*x^4 - 4*x^5). - Colin Barker, Nov 24 2018

EXAMPLE

Some solutions for n=4:

..0..0....1..2....0..0....1..0....0..0....1..1....0..2....2..1....2..0....1..0

..1..2....2..2....0..2....0..0....0..1....2..2....2..0....0..2....0..2....0..1

..2..0....2..2....2..1....2..2....1..2....2..1....1..0....2..0....2..1....1..0

..2..1....2..0....2..1....1..2....2..2....2..1....1..1....2..0....1..2....1..1

..2..2....0..0....2..0....0..2....1..2....0..1....0..0....2..2....1..2....2..1

CROSSREFS

Column 1 of A251010.

Sequence in context: A234832 A234825 A251010 * A211692 A264288 A113707

Adjacent sequences:  A251000 A251001 A251002 * A251004 A251005 A251006

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 29 2014

STATUS

approved

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Last modified June 28 11:37 EDT 2022. Contains 354905 sequences. (Running on oeis4.)