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A269463 Number of length-n 0..4 arrays with no repeated value equal to the previous repeated value. 1
5, 25, 120, 580, 2780, 13300, 63420, 301780, 1433180, 6795700, 32180220, 152216980, 719335580, 3396714100, 16028713020, 75595396180, 356358069980, 1679206088500, 7909957661820, 37249421039380, 175371521796380, 825484323238900 (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) = 7*a(n-1) - 4*a(n-2) - 32*a(n-3).

Empirical g.f.: 5*x*(1 - 2*x - 7*x^2) / ((1 - 4*x)*(1 - 3*x - 8*x^2)). - Colin Barker, Jan 22 2019

EXAMPLE

Some solutions for n=7:

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

..4. .1. .0. .0. .4. .0. .4. .4. .0. .3. .4. .4. .2. .4. .2. .3

..3. .0. .2. .2. .0. .4. .3. .4. .1. .0. .0. .2. .3. .1. .3. .1

..0. .1. .1. .1. .4. .1. .3. .3. .4. .0. .2. .3. .3. .0. .2. .4

..1. .0. .3. .4. .1. .4. .1. .2. .4. .2. .0. .4. .1. .1. .1. .0

..4. .4. .4. .2. .0. .0. .2. .0. .0. .2. .1. .4. .4. .3. .1. .3

..1. .2. .2. .3. .3. .2. .4. .0. .0. .1. .4. .1. .1. .2. .4. .3

CROSSREFS

Column 4 of A269467.

Sequence in context: A269674 A269602 A089927 * A068539 A123871 A268453

Adjacent sequences:  A269460 A269461 A269462 * A269464 A269465 A269466

KEYWORD

nonn

AUTHOR

R. H. Hardin, Feb 27 2016

STATUS

approved

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Last modified September 28 17:43 EDT 2020. Contains 337393 sequences. (Running on oeis4.)