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A251195 Number of (n+1) X (2+1) 0..1 arrays with no 2 X 2 subblock having the minimum of its diagonal elements less than the absolute difference of its antidiagonal elements. 1
25, 86, 310, 1135, 4172, 15353, 56519, 208082, 766105, 2820622, 10384911, 38234978, 140772894, 518295264, 1908250809, 7025765815, 25867346793, 95237963740, 350645538289, 1291000864451, 4753185339819, 17500198099533, 64431935981585 (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) = 2*a(n-1) + 7*a(n-2) - a(n-3) - 7*a(n-4) - a(n-5) for n>6.

Empirical g.f.: x*(25 + 36*x - 37*x^2 - 62*x^3 - 7*x^4 + x^5) / (1 - 2*x - 7*x^2 + x^3 + 7*x^4 + x^5). - Colin Barker, Nov 26 2018

EXAMPLE

Some solutions for n=4:

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

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

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

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

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

CROSSREFS

Column 2 of A251201.

Sequence in context: A081272 A318293 A027026 * A087240 A044212 A044593

Adjacent sequences: A251192 A251193 A251194 * A251196 A251197 A251198

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 30 2014

STATUS

approved

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Last modified February 2 03:35 EST 2023. Contains 359997 sequences. (Running on oeis4.)