A135157 Number of primitive (no repeated characters) and irreducible (not the concatenation of generatable strings) strings obtained from abc by iterated repetition of substrings in place.

1, 0, 2, 0, 3, 1, 4, 0, 5, 2, 6, 0, 7, 3, 8, 0, 9, 6, 10, 0, 11, 12, 12, 4, 13, 24, 14, 23, 15, 54, 16, 91, 17, 149, 18, 326, 19, 484, 20, 1144, 21, 1741, 22, 4015, 23, 6589, 24, 14296, 25, 25299, 26, 52077, 27, 97264, 28, 193781, 29, 373996, 30, 733076

Offset

0,3

Links

Table of n, a(n) for n=0..59.

Index entries for doubling substrings

Crossrefs

Cf. A135473, A135156.

Sequence in context: A110514 A338503 A249122 * A360692 A135156 A328967

Adjacent sequences: A135154 A135155 A135156 * A135158 A135159 A135160

Keyword

nonn

Author

David Applegate and N. J. A. Sloane, Feb 15 2008

Status

approved