Greatest common prime divisor of n and sigma_2(n) = A001157(n), or 1 if the two are relatively prime.
1, 1, 1, 1, 1, 2, 1, 1, 1, 5, 1, 3, 1, 2, 5, 1, 1, 1, 1, 2, 1, 2, 1, 2, 1, 2, 1, 7, 1, 5, 1, 1, 1, 2
1 seqfan posts
Sat Jul 9 16:18:41 CEST 2011 [seqfan] gcd(n, sigma_2(n))