VOOZH
about
URL: https://oeis.org/A269461
⇱ A269461 - OEIS
login
A269461
Number of length-n 0..2 arrays with no repeated value equal to the previous repeated value.
2
3, 9, 24, 66, 174, 462, 1206, 3150, 8166, 21150, 54582, 140718, 362118, 931134, 2391894, 6141006, 15757734, 40420062, 103647606, 265721070, 681097926, 1745555070, 4473092502, 11461604238, 29366557158, 75238139934, 192754700214
(
list
;
graph
;
refs
;
listen
;
history
;
text
;
internal format
)
OFFSET
1,1
COMMENTS
Column 2 of
A269467
.
LINKS
R. H. Hardin,
Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 3*a(n-1) + 2*a(n-2) - 8*a(n-3).
Conjectures from
Colin Barker
, Mar 21 2018: (Start)
G.f.: 3*x*(1 - 3*x^2) / ((1 - 2*x)*(1 - x - 4*x^2)).
a(n) = 2^(-4-n)*(-51*4^(1+n) + (255-57*sqrt(17))*(1-sqrt(17))^n + 3*(1+sqrt(17))^n*(85+19*sqrt(17))) / 17.
(End)
EXAMPLE
Some solutions for n=9:
..1. .1. .0. .2. .1. .0. .1. .2. .2. .1. .1. .0. .2. .2. .0. .2
..1. .2. .1. .2. .2. .1. .0. .1. .1. .0. .1. .2. .0. .1. .1. .1
..0. .2. .2. .1. .1. .2. .1. .1. .0. .0. .0. .1. .1. .1. .0. .1
..2. .0. .2. .2. .2. .2. .2. .0. .0. .1. .2. .2. .1. .0. .1. .2
..2. .1. .0. .0. .0. .1. .2. .2. .2. .2. .0. .0. .2. .0. .0. .0
..1. .0. .2. .1. .1. .0. .0. .2. .1. .2. .0. .1. .1. .2. .2. .0
..2. .1. .1. .1. .0. .2. .2. .1. .1. .0. .1. .0. .0. .2. .1. .2
..0. .1. .2. .0. .0. .1. .1. .0. .0. .2. .2. .1. .2. .1. .1. .2
..1. .0. .1. .0. .1. .0. .0. .1. .1. .1. .2. .0. .0. .1. .2. .0
CROSSREFS
Cf.
A269467
.
Sequence in context:
A269531
A064831
A153582
*
A096168
A051042
A121907
Adjacent sequences:
A269458
A269459
A269460
*
A269462
A269463
A269464
KEYWORD
nonn
AUTHOR
R. H. Hardin
, Feb 27 2016
STATUS
approved
