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A250798 Number of (1+1) X (n+1) 0..1 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
10, 24, 54, 118, 252, 530, 1102, 2272, 4654, 9486, 19260, 38986, 78726, 158672, 319318, 641830, 1288828, 2586018, 5185566, 10393024, 20821470, 41700254, 83493244, 167136538, 334515862, 669424560, 1339484742, 2679997942, 5361659964 (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) = 3*a(n-1) - a(n-2) - 2*a(n-3).

Empirical g.f.: 2*x*(5 - 3*x - 4*x^2) / ((1 - 2*x)*(1 - x - x^2)). - Colin Barker, Nov 20 2018

EXAMPLE

Some solutions for n=4:

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

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

CROSSREFS

Row 1 of A250797.

Sequence in context: A103573 A067728 A058504 * A250576 A126911 A223408

Adjacent sequences:  A250795 A250796 A250797 * A250799 A250800 A250801

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 27 2014

STATUS

approved

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Last modified October 27 13:43 EDT 2021. Contains 348276 sequences. (Running on oeis4.)