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A269466 Number of length-n 0..7 arrays with no repeated value equal to the previous repeated value. 1
8, 64, 504, 3976, 31304, 246232, 1934856, 15190840, 119174216, 934305400, 7320389832, 57325443448, 448697920328, 3510562344184, 27455875247304, 214658236385656, 1677757456358984, 13109740539632632, 102412911071378376 (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) = 13*a(n-1) -28*a(n-2) -98*a(n-3).

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

G.f.: 8*x*(1 - 5*x - 13*x^2) / ((1 - 7*x)*(1 - 6*x - 14*x^2)).

a(n) = 2*(-92*7^n + (345-67*sqrt(23))*(3-sqrt(23))^n + (3+sqrt(23))^n*(345+67*sqrt(23))) / 1127.

(End)

EXAMPLE

Some solutions for n=5:

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

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

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

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

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

CROSSREFS

Column 7 of A269467.

Sequence in context: A269677 A269408 A269605 * A127426 A268456 A126629

Adjacent sequences:  A269463 A269464 A269465 * A269467 A269468 A269469

KEYWORD

nonn

AUTHOR

R. H. Hardin, Feb 27 2016

STATUS

approved

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Last modified June 27 04:37 EDT 2022. Contains 354888 sequences. (Running on oeis4.)