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A223913 Number of n X 3 0..2 arrays with rows and antidiagonals unimodal and columns nondecreasing. 1
22, 158, 666, 2111, 5548, 12752, 26494, 50863, 91634, 156682, 256442, 404415, 617720, 917692, 1330526, 1887967, 2628046, 3595862, 4844410, 6435455, 8440452, 10941512, 14032414, 17819663, 22423594, 27979522, 34638938, 42570751, 51962576 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 3 of A223918.

LINKS

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

FORMULA

Empirical: a(n) = (23/360)*n^6 + (23/40)*n^5 + (205/72)*n^4 + (143/24)*n^3 + (364/45)*n^2 + (82/15)*n - 1.

Conjectures from Colin Barker, Aug 24 2018: (Start)

G.f.: x*(22 + 4*x + 22*x^2 - 3*x^3 - 3*x^4 + 5*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:

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

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

..2..1..1....2..2..2....2..2..1....2..2..2....2..1..1....2..2..1....2..2..2

CROSSREFS

Cf. A223918.

Sequence in context: A027943 A224257 A244868 * A189416 A224185 A185859

Adjacent sequences:  A223910 A223911 A223912 * A223914 A223915 A223916

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 29 2013

STATUS

approved

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Last modified March 19 13:25 EDT 2019. Contains 321330 sequences. (Running on oeis4.)