What is the sum of number of divisors of divisors of number which is smaller than n, such that sum of number of divisors of divisors of this number is maximum?
For example,
g(n) = number of divisors of n
f(12) = g(1) + g(2) + g(3) + g(4) + g(6) + g(12)
f(12) = (1) + (2) + (2) + (3) + (4) + (6) = 18
Can you help about it?