cp's OEIS Frontend

A221522 Number of 0..6 arrays of length n with each element differing from at least one neighbor by 2 or more.

%I A221522 #9 Oct 18 2017 13:28:52
%S A221522 0,30,130,900,5368,33380,205080,1264378,7787228,47975704,295543282,
%T A221522 1820672982,11216042008,69095255496,425653839018,2622194869596,
%U A221522 16153749662332,99513440156936,613041859314376,3776578532115986
%N A221522 Number of 0..6 arrays of length n with each element differing from at least one neighbor by 2 or more.
%C A221522 Column 6 of A221524.
%H A221522 R. H. Hardin, <a href="/A221522/b221522.txt">Table of n, a(n) for n = 1..210</a>
%F A221522 Empirical: a(n) = 3*a(n-1) +14*a(n-2) +29*a(n-3) +28*a(n-4) +a(n-5) +27*a(n-6) +8*a(n-7) +2*a(n-8).
%F A221522 Empirical g.f.: 2*x^2*(15 + 20*x + 45*x^2 - 11*x^3 + 33*x^4 + 9*x^5 + 3*x^6) / (1 - 3*x - 14*x^2 - 29*x^3 - 28*x^4 - x^5 - 27*x^6 - 8*x^7 - 2*x^8). - _Colin Barker_, Oct 18 2017
%e A221522 Some solutions for n=6
%e A221522 ..0....1....6....1....0....6....4....1....3....3....1....4....2....1....5....6
%e A221522 ..4....4....4....4....3....0....6....5....0....5....4....1....5....3....3....2
%e A221522 ..3....3....0....2....2....4....2....0....6....0....1....5....6....1....5....2
%e A221522 ..0....1....4....5....4....4....0....1....4....4....6....1....1....2....5....0
%e A221522 ..0....0....0....4....0....2....6....6....3....5....0....0....2....6....2....2
%e A221522 ..5....3....6....1....6....0....2....0....1....2....4....2....4....4....0....0
%K A221522 nonn
%O A221522 1,2
%A A221522 _R. H. Hardin_, Jan 19 2013