OFFSET
1,1
COMMENTS
It seems that a(n) is the least number for which equation x = p*sopf(x) has exactly n solutions in positive integers not only for prime numbers.
LINKS
Vladimir Letsko, Mathematical Marathon, Problem 227 (in Russian)
EXAMPLE
a(3) = 7 because there are 3 solutions of the equation x = 7*sopf(x), which are {49, 84, 105}, and this is the smallest prime that gives 3 solutions.
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Vladimir Letsko, Jul 16 2020
STATUS
approved