The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A269673 Number of length-n 0..3 arrays with no repeated value differing from the previous repeated value by other than plus or minus one modulo 3+1. 1
 4, 16, 60, 224, 820, 2976, 10700, 38224, 135780, 480176, 1691740, 5941824, 20814740, 72755776, 253836780, 884207024, 3075861700, 10687549776, 37098781820, 128668433824, 445930140660, 1544500542176, 5346546062860, 18499277662224 (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) = 5*a(n-1) - a(n-2) - 15*a(n-3). Conjectures from Colin Barker, Jan 26 2019: (Start) G.f.: 4*x*(1 - x - 4*x^2) / ((1 - 3*x)*(1 - 2*x - 5*x^2)). a(n) = (-20*3^n + (18-7*sqrt(6))*(1-sqrt(6))^n + (1+sqrt(6))^n*(18+7*sqrt(6))) / 15. (End) EXAMPLE Some solutions for n=9: ..3. .0. .2. .0. .2. .0. .1. .0. .1. .3. .2. .2. .1. .3. .0. .0 ..1. .3. .0. .1. .0. .1. .3. .1. .3. .0. .1. .1. .3. .1. .2. .0 ..0. .3. .1. .3. .0. .0. .0. .1. .2. .1. .3. .3. .0. .0. .1. .1 ..2. .0. .2. .3. .1. .3. .3. .0. .0. .2. .2. .1. .3. .1. .3. .3 ..3. .0. .2. .2. .3. .0. .2. .2. .0. .1. .2. .0. .0. .3. .3. .2 ..3. .1. .1. .1. .1. .0. .0. .0. .1. .0. .0. .0. .0. .3. .2. .0 ..0. .2. .0. .0. .0. .3. .3. .3. .1. .2. .2. .3. .3. .1. .1. .3 ..0. .3. .2. .1. .2. .3. .1. .1. .0. .2. .1. .2. .2. .0. .3. .3 ..3. .2. .3. .2. .1. .1. .1. .3. .1. .0. .2. .1. .1. .0. .2. .0 CROSSREFS Column 3 of A269678. Sequence in context: A269635 A267928 A269532 * A231896 A128650 A072335 Adjacent sequences: A269670 A269671 A269672 * A269674 A269675 A269676 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 | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified April 21 09:27 EDT 2024. Contains 371851 sequences. (Running on oeis4.)