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A250521 Number of (n+1)X(2+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
222, 1180, 5029, 18859, 65310, 214812, 682921, 2122743, 6501118, 19720580, 59462069, 178644459, 535616774, 1604254580, 4803055177, 14379531399, 43056528118, 128955131820, 386326404261, 1157662173067, 3469836562702 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
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*(222 - 1928*x + 7379*x^2 - 16515*x^3 + 23687*x^4 - 22151*x^5 + 13066*x^6 - 4404*x^7 + 648*x^8) / ((1 - x)^5*(1 - 2*x)^3*(1 - 3*x)). - Colin Barker, Nov 14 2018
EXAMPLE
Some solutions for n=5:
..2..2..0....2..2..1....1..1..0....2..0..0....2..1..1....2..1..0....2..0..0
..1..2..0....1..1..0....2..2..2....2..0..0....1..0..0....2..2..1....2..1..1
..1..2..0....2..2..1....1..1..1....2..0..1....2..1..1....1..1..0....1..0..0
..1..2..0....0..0..1....1..1..1....2..1..2....2..1..1....0..1..0....0..0..0
..1..2..0....1..1..2....0..0..0....1..0..2....1..0..0....0..1..0....0..0..0
..0..1..2....0..0..1....1..1..1....0..0..2....1..0..2....0..1..2....1..2..2
CROSSREFS
Column 2 of A250527.
Sequence in context: A361628 A101955 A063352 * A043499 A251059 A220230
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 24 2014
STATUS
approved

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Last modified June 25 02:21 EDT 2024. Contains 373691 sequences. (Running on oeis4.)