cp's OEIS Frontend

A183357 One quarter the number of n X 5 1..4 arrays with no two neighbors of any element equal to each other.

%I A183357 #9 Mar 28 2018 08:14:18
%S A183357 108,2304,3888,9216,24192,57600,137088,331776,802944,1937664,4675968,
%T A183357 11289600,27257472,65804544,158864256,383533056,925932672,2235398400,
%U A183357 5396727168,13028852736,31454434944,75937722624,183329877888
%N A183357 One quarter the number of n X 5 1..4 arrays with no two neighbors of any element equal to each other.
%C A183357 Column 5 of A183362.
%H A183357 R. H. Hardin, <a href="/A183357/b183357.txt">Table of n, a(n) for n = 1..200</a>
%F A183357 Empirical: a(n) = 2*a(n-1) + 2*a(n-3) + a(n-4) for n>7.
%F A183357 Empirical g.f.: 36*x*(3 + 58*x - 20*x^2 + 34*x^3 + 29*x^4 - 24*x^5 - 12*x^6) / ((1 + x^2)*(1 - 2*x - x^2)). - _Colin Barker_, Mar 28 2018
%e A183357 Some solutions for 7 X 5 with a(1,1)=1:
%e A183357 ..1..1..2..4..1....1..2..2..3..3....1..2..2..3..3....1..1..3..4..1
%e A183357 ..4..3..3..4..2....1..4..4..1..2....3..4..4..1..1....4..2..2..4..3
%e A183357 ..2..2..1..1..3....2..3..3..1..2....2..1..3..2..2....3..3..1..1..2
%e A183357 ..3..4..4..2..3....4..1..2..4..4....2..1..3..4..4....2..4..4..3..2
%e A183357 ..1..1..3..2..1....3..1..2..3..3....3..4..2..1..1....1..1..2..3..1
%e A183357 ..4..2..3..4..4....2..4..4..1..2....3..4..2..3..3....4..3..2..4..1
%e A183357 ..3..2..1..1..2....2..3..3..1..4....2..1..1..4..2....2..3..1..4..2
%Y A183357 Cf. A183362.
%K A183357 nonn
%O A183357 1,1
%A A183357 _R. H. Hardin_, Jan 04 2011