A183355 One quarter the number of nX3 1..4 arrays with no two neighbors of any element equal to each other.

12, 144, 432, 1296, 3888, 11664, 34992, 104976, 314928, 944784, 2834352, 8503056, 25509168, 76527504, 229582512, 688747536, 2066242608, 6198727824, 18596183472, 55788550416, 167365651248, 502096953744, 1506290861232, 4518872583696

Offset: 1

Author

R. H. Hardin Jan 04 2011

Keywords

• nonn

Comments

Column 3 of A183362

Examples

			Some solutions for 5X3 with a(1,1)=1
..1..1..4....1..1..2....1..4..2....1..2..4....1..1..4....1..3..3....1..2..4
..4..2..2....2..4..3....1..3..2....4..2..1....3..2..4....2..4..1....1..2..4
..3..3..1....2..4..3....2..3..4....4..3..3....3..2..1....2..4..1....3..3..1
..2..4..4....1..1..2....2..1..4....2..1..4....4..4..3....1..3..2....2..4..1
..1..1..3....4..3..2....4..1..3....3..1..4....2..1..3....1..3..2....1..4..2
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..200

Formula

Empirical: a(n)=3*a(n-1) for n>2