0,7

See A137743 for more comments.

Index entries for doubling substrings

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 }

(PARI) A135473(13, 5) /* function defined in A137743...*/

Cf. A137740-A137743, A135473, A137744-A137748.

Sequence in context: A099448 A124806 A059509 this_sequence A005021 A067325 A121525

Adjacent sequences: A137742 A137743 A137744 this_sequence A137746 A137747 A137748

more,nonn

M. F. Hasler (MHasler(AT)univ-ag.fr), Feb 10 2008