OFFSET
1,3
LINKS
Wikipedia, Harmonic mean.
FORMULA
a(n) <= A341810(n).
PROG
(PARI) a(n) = my(k=1); while (denominator(n/sum(j=1, n, 1/eulerphi(k*j))) != 1, k++); k; \\ Michel Marcus, Feb 20 2021
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Feb 20 2021
STATUS
approved