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 A137745 Number of different strings of length n obtained from "abcde" by iteratively duplicating any substring. 4
 0, 0, 0, 0, 0, 1, 5, 19, 66, 218, 700, 2218, 6997, 22064, 69662, 220395, 699090, 2224114, 7098773, 22733498, 73048903, 235504760 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,7 COMMENTS See A137743 for more comments. LINKS EXAMPLE a(k) = 0 for k<5, since no shorter string can be obtained by duplicating a substring. a(5) = # { abcde }, a(6) = # { aabcde, abbcde, abccde, abcdde, abcdee }, a(7) = # { aaabcde, aabbcde, aabccde, aabcdde, aabcdee, ababcde, abbbcde, abbccde, abbcdde, abbcdee, abcbcde, abcccde, abccdde, abccdee, abcdcde, abcddde, abcddee, abcdede, abcdeee } PROG (PARI) A135473(13, 5) /* function defined in A137743...*/ CROSSREFS Cf. A137740-A137743, A135473, A137744-A137748. Sequence in context: A239618 A124806 A059509 * A005021 A067325 A273599 Adjacent sequences:  A137742 A137743 A137744 * A137746 A137747 A137748 KEYWORD more,nonn AUTHOR M. F. Hasler, Feb 10 2008 EXTENSIONS a(14)-a(19) from Lars Blomberg, Jan 12 2013 a(20)-a(21) from Michael S. Branicky, Jan 05 2021 STATUS approved

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Last modified June 15 19:31 EDT 2021. Contains 345049 sequences. (Running on oeis4.)