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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
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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
