A183358 One quarter the number of nX6 1..4 arrays with no two neighbors of any element equal to each other.

324, 9216, 11664, 24336, 57600, 147456, 331776, 746496, 1679616, 3873024, 8856576, 20358144, 46457856, 106502400, 243360000, 557715456, 1275346944, 2921186304, 6682081536, 15300700416, 35007906816, 80147874816, 183403201536

Offset: 1

Author

R. H. Hardin Jan 04 2011

Keywords

• nonn

Comments

Column 6 of A183362

Examples

			Some solutions for 5X6 with a(1,1)=1
..1..3..4..1..1..4....1..4..2..3..1..4....1..1..3..4..1..3....1..2..4..4..1..3
..2..3..4..2..3..3....2..4..1..3..2..4....3..2..2..4..1..2....3..3..1..2..2..3
..2..1..1..2..4..1....2..3..1..4..2..1....4..4..1..3..3..4....4..4..1..3..4..4
..4..4..3..3..4..2....1..3..2..4..3..1....2..3..1..2..2..4....1..2..2..3..1..1
..1..2..2..1..1..3....1..4..2..1..3..2....2..3..4..4..1..1....1..3..4..4..2..3
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..106

Formula

Empirical: a(n)=2*a(n-1)+2*a(n-2)-4*a(n-3)+4*a(n-4)-4*a(n-5)+2*a(n-6)-6*a(n-7)+a(n-10) for n>14