OFFSET
1,7
COMMENTS
Conjecture: a(n) changes sign infinitely often.
LINKS
Seiichi Manyama, Table of n, a(n) for n = 1..10000
FORMULA
If n is not squarefree, a(n) = a(n-1).
a(n) = -1 + 2 * Sum_{k=1..n} A372706(k).
PROG
(PARI) a(n) = sum(j=1, n, sum(k=1, n, moebius(j*k)));
CROSSREFS
KEYWORD
sign,look
AUTHOR
Seiichi Manyama, May 10 2024
STATUS
approved