How do you calculate 3, 8, 24, 48, 120, (168)?

How do you calculate 3, 8, 24, 48, 120, (168)?

3=2^2
8=3^2
24=5^2
48=7^3
120=11^2
168=13^2
2, 3, 5, 7, 11 and 13 are prime numbers