A215074 Number of squarefree words of length n in an 8-ary alphabet, with new values 0..7 introduced in increasing order

1, 1, 2, 4, 12, 40, 154, 660, 3113, 15893, 86857, 502092, 3036032, 19006591, 122119857, 799665333, 5308126648, 35576413852, 240063646519, 1627605038848

Offset

1,3

Comments

Column 7 of A215075.

Links

Table of n, a(n) for n=1..20.

Example

Some solutions for n=9:
..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....2....2....2....2....2....2....2....2....2....2....2....2....2
..3....0....1....3....1....3....3....1....3....3....0....3....1....1....3....0
..4....3....3....4....3....4....4....3....4....0....3....4....3....3....4....3
..0....1....1....5....4....5....1....0....2....2....4....5....4....0....0....4
..3....4....0....4....0....4....5....4....5....4....5....6....0....1....1....0
..1....2....4....0....2....1....3....2....0....5....1....7....5....0....0....5
..2....0....1....6....3....2....0....5....1....4....6....2....1....3....5....2

Crossrefs

Sequence in context: A268955 A268010 A215073 * A215070 A188479 A062962

Adjacent sequences: A215071 A215072 A215073 * A215075 A215076 A215077

Keyword

nonn

Author

R. H. Hardin Aug 02 2012

Status

approved