Numbers n such that n' = p^2-1, with n = semiprime = p*q, n' is the arithmetic derivative of n. Also: semiprimes of the form p*(p^2-p-1).

A190274

Numbers n such that n' = p^2-1, with n = semiprime = p*q, n' is the arithmetic derivative of n. Also: semiprimes of the form p*(p^2-p-1).