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A250987 Number of (n+1) X (1+1) 0..2 arrays with nondecreasing min(x(i,j),x(i,j-1)) in the i direction and nondecreasing absolute value of x(i,j)-x(i-1,j) in the j direction. 1
40, 158, 612, 2323, 8726, 32554, 120930, 447985, 1656600, 6118822, 22583412, 83309947, 307230262, 1132763986, 4175945922, 15393274457, 56738968328, 209129360814, 770792626564, 2840879847779, 10470404185174, 38589657774202 (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) = 6*a(n-1) - 7*a(n-2) - 8*a(n-3) + 7*a(n-4) + 6*a(n-5) + a(n-6).

Empirical g.f.: x*(40 - 82*x - 56*x^2 + 77*x^3 + 56*x^4 + 9*x^5) / ((1 - 2*x - x^2)*(1 - 4*x + 4*x^3 + x^4)). - Colin Barker, Nov 24 2018

EXAMPLE

Some solutions for n=4:

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

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

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

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

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

CROSSREFS

Column 1 of A250994.

Sequence in context: A135848 A089548 A282090 * A300963 A146762 A190073

Adjacent sequences:  A250984 A250985 A250986 * A250988 A250989 A250990

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 29 2014

STATUS

approved

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Last modified November 29 18:41 EST 2021. Contains 349416 sequences. (Running on oeis4.)