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

 

Logo

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 56th year, we are closing in on 350,000 sequences, and we’ve crossed 9,700 citations (which often say “discovered thanks to the OEIS”).

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A269689 Number of length-n 0..7 arrays with no repeated value differing from the previous repeated value by plus or minus one modulo 7+1. 1
8, 64, 512, 4080, 32416, 256880, 2031072, 16027696, 126262688, 993181680, 7802084704, 61219340720, 479867497248, 3758025752944, 29406845849312, 229946299629360, 1796916741666976, 14034055973604080, 109551619154344032 (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) = 14*a(n-1) - 43*a(n-2) - 42*a(n-3).

Conjectures from Colin Barker, Jan 27 2019: (Start)

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

a(n) = (2^(1-n)*(-73*2^(2+n)*7^n - 7*(7-sqrt(73))^n*(-73+9*sqrt(73)) + 7*(7+sqrt(73))^n*(73+9*sqrt(73)))) / 1533.

(End)

EXAMPLE

Some solutions for n=5:

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

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

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

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

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

CROSSREFS

Column 7 of A269690.

Sequence in context: A269618 A269582 A269434 * A269493 A269775 A269655

Adjacent sequences:  A269686 A269687 A269688 * A269690 A269691 A269692

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 03 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 December 4 11:50 EST 2021. Contains 349486 sequences. (Running on oeis4.)