cp's OEIS Frontend

A243600 Number of length n+2 0..3 arrays with no three elements in a row with pattern aba (with a!=b) and new values 0..3 introduced in 0..3 order.

%I A243600 #7 Nov 02 2018 10:18:16
%S A243600 4,10,28,85,269,870,2844,9346,30792,101577,335289,1107066,3655876,
%T A243600 12073706,39875396,131697309,434963141,1436579966,4744692092,
%U A243600 15670638530,51756579024,170940329233,564577491697,1864672682930,6158595344068
%N A243600 Number of length n+2 0..3 arrays with no three elements in a row with pattern aba (with a!=b) and new values 0..3 introduced in 0..3 order.
%H A243600 R. H. Hardin, <a href="/A243600/b243600.txt">Table of n, a(n) for n = 1..210</a>
%F A243600 Empirical: a(n) = 5*a(n-1) - 5*a(n-2) - 3*a(n-3) + 3*a(n-4) + a(n-5).
%F A243600 Empirical g.f.: x*(4 - 10*x - 2*x^2 + 7*x^3 + 2*x^4) / ((1 - x)*(1 - x - x^2)*(1 - 3*x - x^2)). - _Colin Barker_, Nov 02 2018
%e A243600 Some solutions for n=5:
%e A243600 ..0....0....0....0....0....0....0....0....0....0....0....0....0....0....0....0
%e A243600 ..1....0....1....0....0....1....1....1....0....0....0....1....1....1....1....1
%e A243600 ..2....1....2....0....1....2....2....2....1....1....0....2....2....1....1....2
%e A243600 ..3....2....2....1....2....0....3....3....2....1....0....3....3....2....2....2
%e A243600 ..3....2....1....1....2....3....1....3....0....2....1....0....3....3....2....0
%e A243600 ..1....3....0....1....2....3....0....3....3....3....1....0....3....0....0....0
%e A243600 ..2....0....3....0....0....2....2....1....1....1....2....1....3....1....1....2
%Y A243600 Column 3 of A243607.
%K A243600 nonn
%O A243600 1,1
%A A243600 _R. H. Hardin_, Jun 07 2014