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A223835 Number of n X 5 0..1 arrays with rows and antidiagonals unimodal and columns nondecreasing. 1
16, 86, 255, 596, 1240, 2388, 4325, 7436, 12222, 19316, 29499, 43716, 63092, 88948, 122817, 166460, 221882, 291348, 377399, 482868, 610896, 764948, 948829, 1166700, 1423094, 1722932, 2071539, 2474660, 2938476, 3469620, 4075193, 4762780, 5540466 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 5 of A223838.

LINKS

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

FORMULA

Empirical: a(n) = (2/15)*n^5 + (1/6)*n^4 + (19/6)*n^3 + (28/3)*n^2 + (126/5)*n - 36 for n>2.

Conjectures from Colin Barker, Aug 23 2018: (Start)

G.f.: x*(16 - 10*x - 21*x^2 + 36*x^3 + 9*x^4 - 18*x^5 + 2*x^6 + 2*x^7) / (1 - x)^6.

a(n) = 6*a(n-1) - 15*a(n-2) + 20*a(n-3) - 15*a(n-4) + 6*a(n-5) - a(n-6) for n>8.

(End)

EXAMPLE

Some solutions for n=3:

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

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

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

CROSSREFS

Cf. A223838.

Sequence in context: A223962 A252834 A050256 * A224143 A225007 A070052

Adjacent sequences:  A223832 A223833 A223834 * A223836 A223837 A223838

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 27 2013

STATUS

approved

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Last modified October 19 15:50 EDT 2019. Contains 328223 sequences. (Running on oeis4.)