15511295531domain: NAppears in sequencesa(n) = a(n-2) + a(n-1) if that sum is prime. Otherwise, a(n) = a(n-2) + a(n-1) + prime(m-1) + prime(m-2) + ... + prime(s), where a(-1) = a(0) = prime(0) = 1, m = pi(a(n-2)), and s = max(0, 1, 2, ..., m-1) such that the sum is prime.at n=20A337347