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!)
A268940 Number of length-n 0..4 arrays with no repeated value unequal to the previous repeated value plus one mod 4+1. 1
5, 25, 120, 565, 2615, 11950, 54045, 242365, 1079240, 4777225, 21038595, 92244790, 402898865, 1753806625, 7611458520, 32945585965, 142262759615, 612991045150, 2636186279445, 11317111447765, 48506655275240, 207603081203425 (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) - 7*a(n-2) - 20*a(n-3).

Empirical g.f.: 5*x*(1 - 2*x - 4*x^2) / ((1 - 4*x)*(1 - 3*x - 5*x^2)). - Colin Barker, Jan 17 2019

EXAMPLE

Some solutions for n=7:

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

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

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

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

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

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

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

CROSSREFS

Column 4 of A268944.

Sequence in context: A034274 A110212 A344097 * A269636 A269533 A269405

Adjacent sequences:  A268937 A268938 A268939 * A268941 A268942 A268943

KEYWORD

nonn

AUTHOR

R. H. Hardin, Feb 16 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 September 20 13:56 EDT 2021. Contains 347586 sequences. (Running on oeis4.)