Mixed primorial

The mixed primorial is defined as follows:

A(1) = 2

A(2) = 2 + 3 = 5

A(3) = 2 + 3 * 5 = 25

A(4) = 2 + 3 * 5 ^ 7 = 6103515625

A(5) = 2 + 3 * 5 ^ 7 ^^ 11

etc.