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A250522 Number of (n+1)X(3+1) 0..2 arrays with nondecreasing x(i,j)-x(i,j-1) in the i direction and nondecreasing x(i,j)-x(i-1,j) in the j direction. 1
867, 5029, 21955, 82023, 279161, 896191, 2771901, 8374485, 24944039, 73714737, 217061167, 638657339, 1880873517, 5549684027, 16412416857, 48651910233, 144539853387, 430255351197, 1282888681851, 3830445412591, 11449627377217 (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) = 14*a(n-1) - 85*a(n-2) + 294*a(n-3) - 639*a(n-4) + 906*a(n-5) - 839*a(n-6) + 490*a(n-7) - 164*a(n-8) + 24*a(n-9).

Empirical g.f.: x*(867 - 7109*x + 25244*x^2 - 52780*x^3 + 72501*x^4 - 66849*x^5 + 39534*x^6 - 13260*x^7 + 1944*x^8) / ((1 - x)^5*(1 - 2*x)^3*(1 - 3*x)). - Colin Barker, Nov 14 2018

EXAMPLE

Some solutions for n=4:

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

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

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

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

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

CROSSREFS

Column 3 of A250527.

Sequence in context: A038657 A063900 A348818 * A251060 A205224 A165385

Adjacent sequences:  A250519 A250520 A250521 * A250523 A250524 A250525

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 24 2014

STATUS

approved

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Last modified May 23 10:51 EDT 2022. Contains 353975 sequences. (Running on oeis4.)