A215397 Number of length n 0..4 arrays connected end-around, with no sequence of L<n elements immediately followed by itself ("periodic squarefree"), and new values introduced in order 0..4.

1, 1, 1, 3, 6, 26, 84, 324, 1170, 4412, 16313, 61138, 227383, 849667, 3168419, 11831104, 44144206, 164792736, 615027929, 2295714687

Offset

1,4

Comments

Column 4 of A215401.

Links

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

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

Crossrefs

Sequence in context: A148666 A058258 A376970 * A359974 A214309 A005646

Adjacent sequences: A215394 A215395 A215396 * A215398 A215399 A215400

Keyword

nonn

Author

R. H. Hardin, Aug 09 2012

Status

approved