OFFSET
1,1
COMMENTS
The sequence is well defined, since n divides (2^phi(n) - 1)*2^phi(n), where phi is the Euler phi-function, and this latter number looks like 11...100....0.
EXAMPLE
For n=9, we have a(n)=20, and 9*20=180 in base 2 is 10110100, which represents a balanced-parentheses string.
CROSSREFS
KEYWORD
nonn
AUTHOR
Jeffrey Shallit, Sep 25 2021
STATUS
approved