Radicals

 In math, the radical of a positive integer n is defined as the product of the prime numbers dividing n:

The radical of any integer n is the largest square-free divisor of n, and so also described as the square-free kernel of n in math.

Radical numbers for the first few positive integers are 1, 2, 3, 2, 5, 6, 7, 2, 3, 10, ..

The function radicals is multiplicative in math.