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A250975 Number of (n+1) X (1+1) 0..2 arrays with no 2 X 2 subblock having the sum of its diagonal elements less than the absolute difference of its antidiagonal elements. 1
71, 562, 4459, 35381, 280728, 2227408, 17673153, 140225934, 1112609193, 8827890666, 70044049696, 555757777662, 4409606651432, 34987599997513, 277605748165393, 2202636117365747, 17476604492474532, 138666437991429781 (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) - 10*a(n-2) + 13*a(n-3) - 6*a(n-4) + a(n-5).

Empirical g.f.: x*(71 - 77*x + 111*x^2 - 53*x^3 + 9*x^4) / (1 - 9*x + 10*x^2 - 13*x^3 + 6*x^4 - x^5). - Colin Barker, Nov 24 2018

EXAMPLE

Some solutions for n=4:

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

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

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

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

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

CROSSREFS

Column 1 of A250982.

Sequence in context: A142432 A341426 A250982 * A209960 A209953 A251390

Adjacent sequences:  A250972 A250973 A250974 * A250976 A250977 A250978

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 29 2014

STATUS

approved

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Last modified January 25 02:37 EST 2022. Contains 350565 sequences. (Running on oeis4.)