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A224258 Number of n X 4 0..2 arrays with rows and antidiagonals unimodal and columns nondecreasing. 1
46, 548, 3096, 12467, 41012, 116692, 296646, 688533, 1482310, 2995516, 5735542, 10482777, 18398930, 31165238, 51155680, 81650727, 127097568, 193423162, 288406876, 422119879, 607438872, 860642144, 1202096354, 1657042849 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 4 of A224262.

LINKS

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

FORMULA

Empirical: a(n) = (41/4032)*n^8 + (9/112)*n^7 + (349/480)*n^6 + (69/20)*n^5 + (1325/192)*n^4 + (1571/48)*n^3 + (87503/5040)*n^2 - (21949/420)*n + 43 for n>2.

Conjectures from Colin Barker, Aug 29 2018: (Start)

G.f.: x*(46 + 134*x - 180*x^2 + 467*x^3 + 29*x^4 - 416*x^5 + 534*x^6 - 255*x^7 + 61*x^8 - 12*x^9 + 2*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..0..2..0....0..0..1..2....0..0..0..0....0..0..0..0....0..1..1..0

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

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

CROSSREFS

Cf. A224262.

Sequence in context: A055751 A232071 A156892 * A223914 A224186 A027940

Adjacent sequences:  A224255 A224256 A224257 * A224259 A224260 A224261

KEYWORD

nonn

AUTHOR

R. H. Hardin, Apr 02 2013

STATUS

approved

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Last modified August 12 07:45 EDT 2022. Contains 356067 sequences. (Running on oeis4.)