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URL: https://oeis.org/A251084

⇱ A251084 - OEIS

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A251084
Number of (n+1) X (4+1) 0..2 arrays with no 2 X 2 subblock having the sum of its diagonal elements greater than the absolute difference of its antidiagonal elements.
1
420, 1306, 2362, 4718, 8512, 15780, 28616, 52934, 98550, 186788, 358250, 695798, 1363076, 2688996, 5329268, 10596902, 21115770, 42135172, 84151526, 168159190, 336144664, 672082436, 1343919232, 2687549958, 5374762142, 10749132260
OFFSET
1,1
LINKS
FORMULA
Empirical: a(n) = 6*a(n-1) - 13*a(n-2) + 10*a(n-3) + 5*a(n-4) - 14*a(n-5) + 9*a(n-6) - 2*a(n-7) for n>8.
Empirical g.f.: 2*x*(210 - 607*x - 7*x^2 + 1662*x^3 - 2125*x^4 + 886*x^5 + 53*x^6 - 89*x^7) / ((1 - x)^5*(1 + x)*(1 - 2*x)). - Colin Barker, Nov 24 2018
EXAMPLE
Some solutions for n=4:
..1..1..1..1..2....0..1..2..2..2....0..1..1..1..2....0..0..0..1..2
..0..0..0..0..0....1..0..0..0..0....0..0..0..0..1....0..0..0..0..1
..1..1..1..1..1....2..0..0..0..0....0..0..0..0..1....1..0..0..0..1
..2..0..0..0..0....2..0..0..0..0....1..0..0..0..1....2..0..0..0..0
..2..0..0..0..0....2..0..0..0..0....1..0..0..0..0....2..0..0..0..0
CROSSREFS
Column 4 of A251088.
Sequence in context: A392030 A281210 A235233 * A250383 A145678 A160372
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 29 2014
STATUS
approved