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A224039 Number of 3 X n 0..1 arrays with antidiagonals unimodal and rows and diagonals nondecreasing. 1
8, 21, 37, 58, 85, 119, 161, 212, 273, 345, 429, 526, 637, 763, 905, 1064, 1241, 1437, 1653, 1890, 2149, 2431, 2737, 3068, 3425, 3809, 4221, 4662, 5133, 5635, 6169, 6736, 7337, 7973, 8645, 9354, 10101, 10887, 11713, 12580, 13489, 14441, 15437, 16478 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Row 3 of A224038.

LINKS

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

FORMULA

Empirical: a(n) = (1/6)*n^3 + 1*n^2 + (47/6)*n for n>1.

Conjectures from Colin Barker, Aug 26 2018: (Start)

G.f.: x*(8 - 11*x + x^2 + 4*x^3 - x^4) / (1 - x)^4.

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

(End)

EXAMPLE

Some solutions for n=3:

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

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

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

CROSSREFS

Cf. A224038.

Sequence in context: A154894 A241986 A179681 * A279895 A225287 A000567

Adjacent sequences:  A224036 A224037 A224038 * A224040 A224041 A224042

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 30 2013

STATUS

approved

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Last modified May 11 19:29 EDT 2021. Contains 343808 sequences. (Running on oeis4.)