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A269465 Number of length-n 0..6 arrays with no repeated value equal to the previous repeated value. 1
7, 49, 336, 2310, 15834, 108402, 741090, 5060706, 34523202, 235304034, 1602555906, 10906971810, 74188793154, 504367206882, 3427339028610, 23280526483746, 158079249910722, 1073053862250594, 7281968079533826, 49404973360789410 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

FORMULA

Empirical: a(n) = 11*a(n-1) -18*a(n-2) -72*a(n-3).

Conjectures from Colin Barker, Jan 22 2019: (Start)

G.f.: 7*x*(1 - 4*x - 11*x^2) / ((1 - 6*x)*(1 - 5*x - 12*x^2)).

a(n) = (7/657)*2^(-4-n) * (-73*3^n*4^(1+n) + (949-103*sqrt(73))*(5-sqrt(73))^n + (5+sqrt(73))^n*(949+103*sqrt(73))).

(End)

EXAMPLE

Some solutions for n=6:

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

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

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

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

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

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

CROSSREFS

Column 6 of A269467.

Sequence in context: A269676 A269407 A269604 * A268455 A323559 A250349

Adjacent sequences:  A269462 A269463 A269464 * A269466 A269467 A269468

KEYWORD

nonn

AUTHOR

R. H. Hardin, Feb 27 2016

STATUS

approved

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Last modified September 19 11:18 EDT 2021. Contains 347556 sequences. (Running on oeis4.)