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A135156 a(n) = number of strings of length n that can be obtained by starting with abc and repeatedly doubling any substring of length >= 2 in place. 2
1, 0, 2, 0, 3, 1, 4, 0, 5, 2, 6, 1, 7, 3, 8, 9, 9, 7, 10, 34, 11, 36, 12, 136, 13, 190, 14, 567, 15, 1018, 16, 2445, 17, 5474, 18, 11371, 19, 28233, 20, 57961, 21, 143391, 22, 308793, 23, 740519, 24, 1668316 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,3
COMMENTS
A "weakly primitive" version of A135473. Cf. A135017.
Differs from A135017 in that the strings may contain repeated letters.
LINKS
CROSSREFS
Sequence in context: A249122 A135157 A360692 * A328967 A358171 A277707
KEYWORD
nonn
AUTHOR
STATUS
approved

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Last modified March 28 20:05 EDT 2024. Contains 371254 sequences. (Running on oeis4.)