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A223944 Number of n X 3 0..1 arrays with diagonals and antidiagonals unimodal and rows nondecreasing. 1
4, 16, 54, 177, 596, 2024, 6869, 23285, 78942, 267681, 907708, 3078001, 10437337, 35392507, 120014445, 406963770, 1379996360, 4679507294, 15868004855, 53807711762, 182459601684, 618712543947, 2098027226581, 7114318736716 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 3 of A223949.

LINKS

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

FORMULA

Empirical: a(n) = 4*a(n-1) - 2*a(n-2) - a(n-3) + 5*a(n-4) - 8*a(n-5).

Empirical g.f.: x*(4 - 2*x^2 - 3*x^3 - 8*x^4) / (1 - 4*x + 2*x^2 + x^3 - 5*x^4 + 8*x^5). - Colin Barker, Aug 24 2018

EXAMPLE

Some solutions for n=3:

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

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

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

CROSSREFS

Cf. A223949.

Sequence in context: A134968 A238419 A267227 * A127634 A331457 A331452

Adjacent sequences:  A223941 A223942 A223943 * A223945 A223946 A223947

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 29 2013

STATUS

approved

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Last modified April 5 13:26 EDT 2020. Contains 333241 sequences. (Running on oeis4.)