a(n) is the number of solutions to gcd(a^2 + b^2, p) = 1 where p is the n-th prime and 0 <= a,b <= p-1.

A360323

a(n) is the number of solutions to gcd(a^2 + b^2, p) = 1 where p is the n-th prime and 0 <= a,b <= p-1.