OFFSET
1,2
LINKS
Seiichi Manyama, Table of n, a(n) for n = 1..55
PROG
(PARI) a(n) = my(k=1); while (denominator(1/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