OFFSET
0,2
COMMENTS
A border of a string w is a nonempty proper prefix of w that is also a suffix. The SB ("shortest border") factorization of a string w is as follows: if w has no border, then the factorization is just (w). Otherwise, write w = (x)(w')(x) where x is the shortest border of w, and repeat with w'. The length of the factorization is the number of factors. For example, 011011101 = (01)(1)(011)(1)(01), and so the factorization has length 5.
Asymptotically C*2^n, for C = 6.468626906... .
LINKS
Ragnar Groot Koerkamp and Timon Knigge, Isomorphic inversion problem, 2018.
"Slashadam" Reddit user, Palindromity function, April 29 2020.
CROSSREFS
KEYWORD
nonn
AUTHOR
Jeffrey Shallit, Apr 30 2020
EXTENSIONS
a(28)-a(35) from Bert Dobbelaere, May 12 2020
STATUS
approved