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A223616 Number of n X 4 0..1 arrays with rows and columns unimodal. 1
11, 121, 876, 4466, 17594, 57238, 160883, 403159, 921181, 1951247, 3879910, 7312800, 13164932, 22776596, 38059285, 61676477, 97264447, 149698645, 225411536, 332768158, 482506014, 688246274, 967083623, 1340262451, 1833947441 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 4 of A223620.

LINKS

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

FORMULA

Empirical: a(n) = (1/112)*n^8 + (79/1260)*n^7 + (59/180)*n^6 + (299/360)*n^5 + (259/144)*n^4 + (821/360)*n^3 + (7219/2520)*n^2 + (767/420)*n + 1.

Conjectures from Colin Barker, Aug 21 2018: (Start)

G.f.: x*(11 + 22*x + 183*x^2 + 14*x^3 + 158*x^4 - 56*x^5 + 35*x^6 - 8*x^7 + x^8) / (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>9.

(End)

EXAMPLE

Some solutions for n=4:

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

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

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

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

CROSSREFS

Cf. A223620.

Sequence in context: A221964 A223640 A223633 * A223665 A068179 A293891

Adjacent sequences:  A223613 A223614 A223615 * A223617 A223618 A223619

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 24 2013

STATUS

approved

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Last modified January 23 04:16 EST 2020. Contains 331168 sequences. (Running on oeis4.)