A215070 Number of squarefree words of length n in an n-ary alphabet, with new values 0..n-1 introduced in increasing order.

1, 1, 2, 4, 12, 40, 154, 660, 3114, 15930, 87645, 514851, 3211220, 21166029, 146849903, 1068808441, 8136559688, 64621235409, 534207882566

Offset: 1

Author

R. H. Hardin, Aug 02 2012

Keywords

• nonn

Comments

Diagonal of A215075.

Examples

			Some solutions for n=6:
..0....0....0....0....0....0....0....0....0....0....0....0....0....0....0....0
..1....1....1....1....1....1....1....1....1....1....1....1....1....1....1....1
..2....2....2....0....0....2....2....0....2....0....0....2....2....0....2....2
..1....1....3....2....2....0....3....2....3....2....2....3....3....2....1....1
..0....0....0....3....1....1....4....3....4....0....3....2....1....3....0....3
..1....3....2....0....0....3....5....4....0....1....2....0....2....1....2....4