OFFSET
1,4
COMMENTS
Asymmetric bracelets are those primitive (period n) bracelets that when turned over are different from themselves.
LINKS
Andrew Howroyd, Table of n, a(n) for n = 1..200
FORMULA
Moebius transform of A326895.
EXAMPLE
For n = 4, the six asymmetric bracelets are 1123, 1223, 1233, 1234, 1243, 1324.
PROG
(PARI) \\ U(n, k) is A309528
U(n, k)={sumdiv(n, d, moebius(n/d)*(k^d/n - if(d%2, k^((d+1)/2), (k+1)*k^(d/2)/2)))/2}
a(n)={sum(k=1, n, U(n, k)*sum(r=k, n, binomial(r, k)*(-1)^(r-k)))}
CROSSREFS
KEYWORD
nonn
AUTHOR
Andrew Howroyd, Sep 12 2019
STATUS
approved