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URL: https://oeis.org/A229796

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A229796
Number of 3 X 3 0..n arrays with rows and columns in lexicographically nondecreasing order.
1
45, 1169, 14178, 102251, 520017, 2066505, 6842284, 19692165, 50724037, 119421753, 261015470, 535936479, 1043365337, 1940082033, 3466044984, 5978361865, 9995569629, 16254413569, 25781605914, 39983353235, 60755768865, 90619631609
OFFSET
1,1
LINKS
FORMULA
Empirical: a(n) = (1/20)*n^9 + (11/24)*n^8 + (329/180)*n^7 + (1601/360)*n^6 + (545/72)*n^5 + (347/36)*n^4 + (3367/360)*n^3 + (313/45)*n^2 + (37/10)*n + 1.
Conjectures from Colin Barker, Sep 21 2018: (Start)
G.f.: x*(45 + 719*x + 4513*x^2 + 7676*x^3 + 4687*x^4 + 420*x^5 + 121*x^6 - 46*x^7 + 10*x^8 - x^9) / (1 - x)^10.
a(n) = 10*a(n-1) - 45*a(n-2) + 120*a(n-3) - 210*a(n-4) + 252*a(n-5) - 210*a(n-6) + 120*a(n-7) - 45*a(n-8) + 10*a(n-9) - a(n-10) for n>10.
(End)
EXAMPLE
Some solutions for n=2:
..0..1..1....0..0..2....0..0..0....1..1..2....1..1..1....0..2..2....0..2..2
..0..1..2....1..2..1....0..2..2....1..2..0....1..1..2....1..0..2....1..0..1
..2..1..0....2..0..1....0..2..2....2..0..1....2..2..1....1..2..2....1..2..1
CROSSREFS
Row 3 of A229794.
Sequence in context: A327510 A215769 A320822 * A143400 A226981 A173000
KEYWORD
nonn
AUTHOR
R. H. Hardin, Sep 29 2013
STATUS
approved