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

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A221510 Number of 0..3 arrays of length n with each element differing from at least one neighbor by 2 or more, starting with 0. 1

%I #10 Oct 18 2017 13:27:48

%S 0,2,3,12,30,89,248,706,1995,5652,15998,45297,128240,363074,1027923,

%T 2910236,8239390,23327177,66043368,186980482,529374875,1498754084,

%U 4243238398,12013359841,34011950560,96293859202,272624979363

%N Number of 0..3 arrays of length n with each element differing from at least one neighbor by 2 or more, starting with 0.

%C Column 3 of A221515.

%H R. H. Hardin, <a href="/A221510/b221510.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = a(n-1) +4*a(n-2) +3*a(n-3) +a(n-4).

%F Empirical g.f.: x^2*(2 + x + x^2) / ((1 + x)*(1 - 2*x - 2*x^2 - x^3)). - _Colin Barker_, Oct 18 2017

%e Some solutions for n=6

%e ..0....0....0....0....0....0....0....0....0....0....0....0....0....0....0....0

%e ..2....2....2....2....2....3....2....2....3....3....2....3....3....2....3....3

%e ..3....0....2....1....2....0....0....3....1....3....3....2....0....1....2....3

%e ..0....2....0....3....0....3....1....1....0....1....1....0....3....3....0....1

%e ..3....2....2....0....3....0....3....1....3....3....0....3....3....3....0....0

%e ..0....0....0....3....1....2....1....3....0....0....2....0....1....1....2....3

%K nonn

%O 1,2

%A _R. H. Hardin_, Jan 18 2013

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.

License Agreements, Terms of Use, Privacy Policy. .

Last modified April 19 02:01 EDT 2024. Contains 371782 sequences. (Running on oeis4.)