login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A267226 Number of length-n 0..2 arrays with no following elements greater than or equal to the first repeated value. 1
3, 9, 21, 47, 103, 223, 479, 1023, 2175, 4607, 9727, 20479, 43007, 90111, 188415, 393215, 819199, 1703935, 3538943, 7340031, 15204351, 31457279, 65011711, 134217727, 276824063, 570425343, 1174405119, 2415919103, 4966055935 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 2 of A267232.

LINKS

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

FORMULA

Empirical: a(n) = 5*a(n-1) -8*a(n-2) +4*a(n-3) for n>4.

Conjectures from Colin Barker, Feb 05 2018: (Start)

G.f.: x*(3 - 6*x + 2*x^3) / ((1 - x)*(1 - 2*x)^2).

a(n) = 2^(n+1) + 2^(n-2)*n - 1 for n>1.

(End)

EXAMPLE

Some solutions for n=6:

  1  0  0  1  2  0  1  2  1  1  0  2  1  1  2  2

  0  2  1  2  0  2  2  1  0  2  2  1  2  0  0  1

  2  2  2  0  1  0  1  2  1  1  0  0  0  2  2  0

  0  0  0  2  2  1  2  0  0  2  1  1  2  2  2  1

  2  0  2  1  1  1  0  2  1  1  0  1  0  1  1  2

  1  1  1  1  0  0  1  1  1  1  2  0  1  1  0  0

CROSSREFS

Cf. A267232.

Sequence in context: A262197 A014286 A000714 * A273845 A090984 A319781

Adjacent sequences:  A267223 A267224 A267225 * A267227 A267228 A267229

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 12 2016

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified July 5 19:02 EDT 2020. Contains 335473 sequences. (Running on oeis4.)