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

1,1

Comments

Column 6 of A183362

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

Example

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

Crossrefs

Sequence in context: A064197 A233639 A203374 * A128381 A128992 A221399

Adjacent sequences: A183355 A183356 A183357 * A183359 A183360 A183361

Keyword

nonn

Author

R. H. Hardin Jan 04 2011

Status

approved