Primitive Prime Factor

Given an integer sequence , a prime number is said to be a primitive prime factor of the term if divides but does not divide any for . It is possible for a term to have zero, one, or many primitive prime factors.

For example, the prime factors of the sequence are summarized in the following table (OEIS A005529).

		prime factorization	prime factors	primitive prime factors
1	2	2	2	2
2	5	5	5	5
3	10		2, 5
4	17	17	17	17
5	26		2, 13	13
6	37	37	37	37
7	50		2, 5
8	65		5, 13
9	82		2, 41	41
10	101	101	101	101