A183354 One quarter the number of nX2 1..4 arrays with no two neighbors of any element equal to each other

4, 36, 144, 576, 2304, 9216, 36864, 147456, 589824, 2359296, 9437184, 37748736, 150994944, 603979776, 2415919104, 9663676416, 38654705664, 154618822656, 618475290624, 2473901162496, 9895604649984, 39582418599936, 158329674399744

Offset

1,1

Comments

Column 2 of A183362

Links

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

Formula

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

Example

Some solutions for 5X2 with a(1,1)=1
..1..1....1..3....1..2....1..3....1..3....1..2....1..4....1..2....1..3....1..3
..4..2....4..2....4..4....4..4....4..2....1..2....3..3....4..3....2..2....4..3
..3..3....4..2....3..3....3..2....4..1....4..4....2..2....2..1....4..1....4..2
..1..1....3..1....1..1....1..2....2..3....2..3....1..1....2..1....4..1....3..2
..2..4....2..1....2..2....1..3....1..3....1..1....4..4....3..4....2..3....3..1

Crossrefs

Sequence in context: A173961 A340661 A035287 * A204504 A083223 A102263

Adjacent sequences: A183351 A183352 A183353 * A183355 A183356 A183357

Keyword

nonn

Author

R. H. Hardin Jan 04 2011

Status

approved