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A224185 Number of n X 3 0..2 arrays with rows unimodal and columns nondecreasing. 1
22, 158, 684, 2205, 5852, 13524, 28176, 54153, 97570, 166738, 272636, 429429, 655032, 971720, 1406784, 1993233, 2770542, 3785446, 5092780, 6756365, 8849940, 11458140, 14677520, 18617625, 23402106, 29169882, 36076348, 44294629, 54016880 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 3 of A224190.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..210

FORMULA

Empirical: a(n) = (23/360)*n^6 + (27/40)*n^5 + (205/72)*n^4 + (49/8)*n^3 + (319/45)*n^2 + (21/5)*n + 1.

Conjectures from Colin Barker, Aug 29 2018: (Start)

G.f.: x*(22 + 4*x + 40*x^2 - 35*x^3 + 21*x^4 - 7*x^5 + x^6) / (1 - x)^7.

a(n) = 7*a(n-1) - 21*a(n-2) + 35*a(n-3) - 35*a(n-4) + 21*a(n-5) - 7*a(n-6) + a(n-7) for n>7.

(End)

EXAMPLE

Some solutions for n=3.

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

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

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

CROSSREFS

Cf. A224190.

Sequence in context: A244868 A223913 A189416 * A185859 A173393 A141306

Adjacent sequences:  A224182 A224183 A224184 * A224186 A224187 A224188

KEYWORD

nonn

AUTHOR

R. H. Hardin, Apr 01 2013

STATUS

approved

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Last modified March 21 22:19 EDT 2019. Contains 321382 sequences. (Running on oeis4.)