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A224141 Number of n X 3 0..1 arrays with rows and antidiagonals unimodal and columns nondecreasing. 1
7, 22, 49, 92, 155, 242, 357, 504, 687, 910, 1177, 1492, 1859, 2282, 2765, 3312, 3927, 4614, 5377, 6220, 7147, 8162, 9269, 10472, 11775, 13182, 14697, 16324, 18067, 19930, 21917, 24032, 26279, 28662, 31185, 33852, 36667, 39634, 42757, 46040, 49487, 53102 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 3 of A224146.

LINKS

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

FORMULA

Empirical: a(n) = (2/3)*n^3 + 2*n^2 + (13/3)*n.

Conjectures from Colin Barker, Aug 27 2018: (Start)

G.f.: x*(7 - 6*x + 3*x^2) / (1 - x)^4.

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

(End)

EXAMPLE

Some solutions for n=3:

..0..0..0....0..0..0....0..1..1....0..1..0....0..0..1....0..1..0....0..0..1

..0..0..0....0..0..0....1..1..1....0..1..1....0..0..1....0..1..0....1..1..1

..0..0..1....1..1..1....1..1..1....1..1..1....0..1..1....0..1..0....1..1..1

CROSSREFS

Cf. A224146.

Sequence in context: A014073 A288114 A129109 * A002412 A211652 A211650

Adjacent sequences:  A224138 A224139 A224140 * A224142 A224143 A224144

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 31 2013

STATUS

approved

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Last modified August 23 00:50 EDT 2019. Contains 326211 sequences. (Running on oeis4.)