MathDB

Let

d(n)

be the sum of positive integers divisors of number

n

and

\phi(n)

the quantity of integers in the interval

[0,n]

such that these integers are coprime with

n

. For instance

d(6)=12

and

\phi(7)=6

. Determine if the set of the integers

n

such that,

d(n)\cdot \phi (n)

is a perfect square, is finite or infinite set.

Problem Statement