A183354 - OEIS

%I #7 Mar 31 2012 12:35:50

%S 4,36,144,576,2304,9216,36864,147456,589824,2359296,9437184,37748736,

%T 150994944,603979776,2415919104,9663676416,38654705664,154618822656,

%U 618475290624,2473901162496,9895604649984,39582418599936,158329674399744

%N One quarter the number of nX2 1..4 arrays with no two neighbors of any element equal to each other

%C Column 2 of A183362

%H R. H. Hardin, <a href="/A183354/b183354.txt">Table of n, a(n) for n = 1..200</a>

%F Empirical: a(n)=4*a(n-1) = A002063(n-1) for n>2

%e Some solutions for 5X2 with a(1,1)=1

%e ..1..1....1..3....1..2....1..3....1..3....1..2....1..4....1..2....1..3....1..3

%e ..4..2....4..2....4..4....4..4....4..2....1..2....3..3....4..3....2..2....4..3

%e ..3..3....4..2....3..3....3..2....4..1....4..4....2..2....2..1....4..1....4..2

%e ..1..1....3..1....1..1....1..2....2..3....2..3....1..1....2..1....4..1....3..2

%e ..2..4....2..1....2..2....1..3....1..3....1..1....4..4....3..4....2..3....3..1

%K nonn

%O 1,1

%A _R. H. Hardin_ Jan 04 2011