Gaps in semigroups

In this paper we investigate the behaviour of the gaps in numerical semigroups. We will give an explicit formula for the ith gap of a semigroup generated by k+1 consecutive integers (generalizing a result due to Brauer) as well as for a special numerical semigroup of three generators. It is also proved that the number of gaps of the numerical semigroup generated by integers p and q with g.c.d.(p,q)=1, in the interval pq-(k+1)(p+q),…,pq-k(p+q)] is equals to