OFFSET
1,2
LINKS
FORMULA
a(n) = 1/(7*n) * Sum_{d|n, gcd(d,7)=1} mu(d) * 7^(n/d).
PROG
(PARI) a(n) = sumdiv(n, d, (gcd(d, 7)==1)*(moebius(d)*7^(n/d)))/(7*n);
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, May 29 2024
STATUS
approved