OFFSET
2,1
COMMENTS
Also the number of infinite words that can be formed from (123..n)* by taking every 2^k-th term from some initial index i, with i and k nonnegative. (Follows from Case 2 of Theorem 2.1) - Charlie Neder, Feb 28 2019
LINKS
Charlie Neder, Table of n, a(n) for n = 2..128
Savinien Kreczman, Luca Prigioniero, Eric Rowland, and Manon Stipulanti, Magic numbers in periodic sequences, Univ. Liège (Belgium, 2023).
Klaus Sutner and Sam Tetruashvili, Inferring Automatic Sequences.
FORMULA
a(2^k) = 2^(k+1) - 1. It appears that a(n) <= n(n-1), with equality if and only if n is a prime with primitive root 2 (A001122). - Charlie Neder, Feb 28 2019
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Oct 07 2012
EXTENSIONS
a(11)-a(20) added (see Inferring Automatic Sequences) by Vincenzo Librandi, Nov 18 2012
a(21)-a(54) from Charlie Neder, Feb 28 2019
STATUS
approved