OFFSET
1,56
COMMENTS
a(n) is zero for all prime powers (A000961), but also for many other numbers.
LINKS
EXAMPLE
Divisors of 56 larger than 1 are [2, 4, 7, 8, 14, 28, 56]. When A297167 is applied to each, one obtains values: [0, 1, 3, 2, 3, 4, 5], of which 6 values are distinct (as one of them, 3, occurs twice). On the other hand, 56 = 2 * 2 * 2 * 7 has four prime factors in total, thus a(56) = 6 - 4 = 2.
PROG
CROSSREFS
KEYWORD
nonn
AUTHOR
Antti Karttunen, Feb 19 2019
STATUS
approved