A215071 Number of squarefree words of length n in a 5-ary alphabet, with new values 0..4 introduced in increasing order

1, 1, 2, 4, 12, 39, 138, 503, 1864, 6936, 25868, 96512, 360203, 1344408, 5018051, 18729944, 69910398, 260943079, 973980990, 3635421345, 13569354266, 50648137765, 189046143161

Offset

1,3

Comments

Column 4 of A215075

Links

Table of n, a(n) for n=1..23.

Example

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....2....0....2....2....2....0....2....2....0....2....2....0....2
..0....3....3....1....2....3....3....1....2....1....0....2....0....3....2....3
..1....4....0....3....3....0....0....3....3....3....3....3....2....2....0....1
..0....0....1....2....0....2....3....4....1....0....4....4....1....4....3....0

Crossrefs

Sequence in context: A108532 A213058 A268069 * A180487 A000940 A008404

Adjacent sequences: A215068 A215069 A215070 * A215072 A215073 A215074

Keyword

nonn

Author

R. H. Hardin Aug 02 2012

Status

approved