A215073 Number of squarefree words of length n in a 7-ary alphabet, with new values 0..6 introduced in increasing order.

1, 1, 2, 4, 12, 40, 154, 659, 3085, 15438, 81200, 442206, 2465945, 13968206, 79933735, 460447075, 2663586832, 15450089345, 89773528848, 522212524474

Offset: 1

Author

R. H. Hardin Aug 02 2012

Keywords

• nonn

Comments

Column 6 of A215075

Examples

			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
..0....2....2....2....0....2....0....2....0....2....2....0....2....2....2....2
..2....3....3....0....2....3....2....3....2....3....0....2....3....1....0....0
..3....2....0....3....3....2....3....2....0....4....3....3....1....3....2....3
..4....0....4....4....0....4....2....1....3....0....4....4....2....1....1....2
..5....4....5....5....2....2....1....0....1....3....3....3....0....4....2....0
..2....5....2....1....0....3....0....2....2....4....0....5....4....0....3....1
..5....1....4....5....3....2....3....1....1....3....2....6....3....3....4....4