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A267466 Number of length-n 0..3 arrays with no following elements larger than the first repeated value. 1
4, 16, 58, 204, 712, 2490, 8770, 31200, 112300, 409254, 1510102, 5638956, 21290368, 81183858, 312262954, 1210023672, 4718194516, 18492663102, 72787129726, 287468548548, 1138446338344, 4518338475786, 17963524388818, 71514144464784 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 3 of A267471.

LINKS

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

FORMULA

Empirical: a(n) = 13*a(n-1) -65*a(n-2) +155*a(n-3) -174*a(n-4) +72*a(n-5).

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

G.f.: 2*x*(2 - 18*x + 55*x^2 - 65*x^3 + 23*x^4) / ((1 - x)*(1 - 2*x)*(1 - 3*x)^2*(1 - 4*x)).

a(n) = (-18 - 9*2^(1+n) + 50*3^n + 9*4^n + 4*3^n*n) / 36.

(End)

EXAMPLE

Some solutions for n=7:

..0....1....1....0....3....3....3....1....2....0....1....0....1....3....2....3

..3....3....0....3....3....1....3....2....3....2....0....3....3....3....0....3

..1....3....1....0....0....3....1....3....0....3....1....1....3....3....3....3

..0....0....1....3....3....3....0....3....3....3....3....0....1....2....3....3

..3....1....0....2....2....1....0....0....2....3....0....1....0....0....3....3

..2....0....0....3....2....3....3....0....2....0....3....1....2....0....3....2

..0....1....1....0....0....1....2....1....2....2....3....0....0....3....2....0

CROSSREFS

Cf. A267471.

Sequence in context: A126644 A168583 A092688 * A255299 A123889 A180143

Adjacent sequences:  A267463 A267464 A267465 * A267467 A267468 A267469

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 15 2016

STATUS

approved

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Last modified September 22 02:48 EDT 2021. Contains 347605 sequences. (Running on oeis4.)