Let a and b be fixed positive
integers. Let n = p1a1p2a2⋯pxax be the canonical representation of n > 1 and let Ra,b
denote the set of all n with the property that each exponent ai(1 ≦ i ≦ r) is either a
multiple of a or is contained in the progression at + b, t ≧ 0. It is clear that
R2,3= L, the set of square-full integers; that is, the set of all n with property
that each prime factor of n divides n to at least the second power. Thus
the elements of Ra,b may be called generalized square-full integers. This
generalization of square-full integers has been given by E. Cohen in 1963, who also
established asymptotic formulae for Ra,b(x), the enumerative function of the set
Ra,b, in various cases. In this paper, we improve the 0-estimates of the error
terms in the asymptotic formulae for Ra,b(x) established by E. Cohen in
some cases and further improve them on the assumption of the Riemann
hypothesis.