A214941 Number of squarefree words of length n in a 7-ary alphabet

7, 42, 252, 1470, 8610, 50190, 292740, 1706250, 9946020, 57970080, 337883700, 1969343880, 11478292770, 66900843240, 389929523550, 2272690998690

Offset

1,1

Comments

Column 6 of A214943

Links

Table of n, a(n) for n=1..16.

Example

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

Crossrefs

Sequence in context: A054890 A102594 A053142 * A162941 A094168 A163345

Adjacent sequences: A214938 A214939 A214940 * A214942 A214943 A214944

Keyword

nonn

Author

R. H. Hardin Jul 30 2012

Status

approved