Let an=n2+1a_n = n^2 + 1an=n2+1 and bn=(n+1)2+1b_n = (n+1)^2 + 1bn=(n+1)2+1 for any integer nnn. What is the set of all possible values of gcd(an,bn)\gcd(a_n, b_n)gcd(an,bn)?
{1, 5}
{1, 2}
{1, 2, 5}
{1, 13}