On the number of prime divisors of the iterates of the Carmichael function.
On the number of prime divisors of the order of elliptic curves modulo p
On the number of prime factors of a finite arithmetical progression
On the number of prime factors of integers of the form ab + 1
On the number of primitive Pythagorean triangles
On the number of primitive λ-roots
On the number of solutions of N - p = Pr.
On the Number of Solutions of p + h = Pr.
On the number of subgroups of finite abelian groups
Letwhere denotes the number of subgroups of all abelian groups whose order does not exceed and whose rank does not exceed , and is the error term. It is proved that
On the number of y-smooth natural numbers ... representable as a sum of two integer squares.
On the numbers that are representable as the sum of two cubes.
On the number-theoretic functions ν(n) and Ω(n)
On the Oesterlé-Masser Conjecture.
On the orbits of Singer groups and their subgroups.
On the order of magnitude of the difference between consecutive prime numbers
On the order of the Mertens function.
On the order of unimodular matrices modulo integers
On the order of vanishing of modular -functions at the critical point
On the problem
On the pair correlation conjecture for zeros of the Riemann zeta-function.