A305595 Number of length-n cyclic ternary words containing no abelian cubes.

3, 6, 8, 15, 30, 67, 126, 261, 540, 1101, 2442

Offset

1,1

Comments

Two words are considered identical in the cyclic sense if one is a cyclic shift of the other.

An abelian cube is a word of the form x x' x'' where x' and x'' are permutations of x.

Links

Table of n, a(n) for n=1..11.

Example

For n = 4 the a(4) = 15 such words are {0011, 0012, 0021, 0022, 0101, 0102, 0112, 0121, 0122, 0202, 0211, 0212, 0221, 1122, 1212}.

Crossrefs

Sequence in context: A117148 A376480 A343272 * A320687 A340494 A039567

Adjacent sequences: A305592 A305593 A305594 * A305596 A305597 A305598

Keyword

nonn,more

Author

Jeffrey Shallit, Jun 05 2018

Status

approved