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A267231 Number of length-n 0..7 arrays with no following elements greater than or equal to the first repeated value. 1
8, 64, 476, 3472, 25088, 180292, 1291052, 9222184, 65755592, 468196540, 3330042548, 23664113536, 168042120176, 1192574364148, 8459259667964, 59977781663128, 425093823838040, 3011867733313516, 21333411555220100 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 7 of A267232.

LINKS

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

FORMULA

Empirical: a(n) = 35*a(n-1) -518*a(n-2) +4214*a(n-3) -20489*a(n-4) +60515*a(n-5) -104992*a(n-6) +96516*a(n-7) -35280*a(n-8) for n>9.

Conjectures from Colin Barker, Feb 05 2018: (Start)

G.f.: 4*x*(2 - 54*x + 595*x^2 - 3437*x^3 + 11088*x^4 - 19495*x^5 + 16287*x^6 - 3546*x^7 - 1260*x^8) / ((1 - x)*(1 - 2*x)*(1 - 3*x)*(1 - 4*x)*(1 - 5*x)*(1 - 6*x)*(1 - 7*x)^2).

a(n) = (-7*(70 + 21*2^(1+n) + 35*3^n + 35*2^(1+n)*3^n + 35*4^n + 42*5^n - 627*7^n) + 60*7^n*n)/2940 for n>1.

(End)

EXAMPLE

Some solutions for n=6:

..2....2....6....2....0....6....6....2....3....4....4....6....4....2....2....6

..7....7....3....6....4....4....3....7....0....2....3....4....7....7....5....7

..4....0....1....0....6....6....4....2....6....0....4....3....0....4....6....5

..6....7....3....5....7....4....4....4....5....5....0....2....5....0....4....2

..2....3....4....4....1....5....0....3....6....7....4....5....4....5....3....1

..4....6....6....0....3....1....3....5....2....7....4....2....3....0....0....7

CROSSREFS

Cf. A267232.

Sequence in context: A223564 A146885 A122093 * A267470 A227591 A268943

Adjacent sequences:  A267228 A267229 A267230 * A267232 A267233 A267234

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 12 2016

STATUS

approved

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Last modified May 7 00:51 EDT 2021. Contains 343617 sequences. (Running on oeis4.)