The modular numerical semigroup S(2,6) = 〈3,4,5〉 is pseudo-symmetric. Thus Corollary 60 of the paper is false, since it asserts that S(a,ab) is not pseudo-symmetric for any positive integers a,b > 1. The mistake comes from part (ii) of Proposition 58, which should read

(The sign on right-hand side of this equality was incorrect.)

Authors