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A224014 Number of 4 X n 0..2 arrays with rows nondecreasing and antidiagonals unimodal. 1
81, 1296, 7378, 28541, 90051, 245055, 595822, 1325316, 2742301, 5343468, 9896484, 17548273, 29963249, 49496631, 79408380, 124123708, 189546519, 283432552, 415829406, 599591037, 850974727, 1190328935, 1642880850, 2239632876 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Row 4 of A224012.

LINKS

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

FORMULA

Empirical: a(n) = (41/4032)*n^8 + (55/336)*n^7 + (733/480)*n^6 + (1037/120)*n^5 + (4789/192)*n^4 + (2125/48)*n^3 + (216821/5040)*n^2 + (9329/210)*n + 4 for n>2.

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

G.f.: x*(81 + 567*x - 1370*x^2 + 1991*x^3 + 132*x^4 - 4590*x^5 + 7855*x^6 - 6900*x^7 + 3514*x^8 - 990*x^9 + 120*x^10) / (1 - x)^9.

a(n) = 9*a(n-1) - 36*a(n-2) + 84*a(n-3) - 126*a(n-4) + 126*a(n-5) - 84*a(n-6) + 36*a(n-7) - 9*a(n-8) + a(n-9) for n>11.

(End)

EXAMPLE

Some solutions for n=3:

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

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

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

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

CROSSREFS

Cf. A224012.

Sequence in context: A232876 A224355 A016768 * A059977 A231912 A116205

Adjacent sequences:  A224011 A224012 A224013 * A224015 A224016 A224017

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 30 2013

STATUS

approved

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Last modified September 18 18:15 EDT 2019. Contains 327178 sequences. (Running on oeis4.)