On the non-linear sieve
On the Number of Solutions of p + h = Pr.
On the numbers that are representable as the sum of two cubes.
On the range of Carmichael's universal-exponent function
Let λ denote Carmichael’s function, so λ(n) is the universal exponent for the multiplicative group modulo n. It is closely related to Euler’s φ-function, but we show here that the image of λ is much denser than the image of φ. In particular the number of λ-values to x exceeds for all large x, while for φ it is equal to , an old result of Erdős. We also improve on an earlier result of the first author and Friedlander giving an upper bound for the distribution of λ-values.
On the representation of a number in the form x^2+y^2+p^2+q^2 where p, q are odd primes
On the switching principle in sieve theory.
On the third iterates of the φ- and σ-functions
On twin almost primes
On zeros of functions satisfying certain differential-difference equations