A190919 Number of permutations of n copies of 1..4 introduced in order 1..4 with no element equal to another within a distance of 2

1, 10, 109, 1277, 15743, 201562, 2655555, 35772051, 490468025, 6822301766, 96037376333, 1365601216463, 19585937393943, 283004879815278, 4115869618377271, 60201892791282135, 885032788096094565

Offset

1,2

Links

R. H. Hardin, Table of n, a(n) for n = 1..121

Example

All solutions for n=2
..1....1....1....1....1....1....1....1....1....1
..2....2....2....2....2....2....2....2....2....2
..3....3....3....3....3....3....3....3....3....3
..4....4....4....4....1....4....4....4....1....4
..2....2....2....1....4....1....1....1....4....2
..1....3....1....3....2....2....2....3....3....3
..3....4....4....2....3....4....3....4....2....1
..4....1....3....4....4....3....4....2....4....4

Crossrefs

Sequence in context: A078922 A199760 A082181 * A095740 A075508 A095176

Adjacent sequences: A190916 A190917 A190918 * A190920 A190921 A190922

Keyword

nonn

Author

R. H. Hardin May 23 2011

Status

approved