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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
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 (list; graph; refs; listen; history; text; internal format)
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: A249738 A110514 A249122 * A135156 A328967 A277707

Adjacent sequences:  A135154 A135155 A135156 * A135158 A135159 A135160

KEYWORD

nonn

AUTHOR

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

STATUS

approved

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Last modified March 30 09:49 EDT 2020. Contains 333125 sequences. (Running on oeis4.)