64498domain: NAppears in sequencesa(n) = (1/24)*(n+1)*(n+6)*(n^3+26*n^2+225*n+636).at n=12A090948Numbers n such that sigma(n) = phi'(n), where sigma(n) is the sum of the divisors of n and phi'(n) is the arithmetic derivative of the Euler totient function of n.at n=6A261432