RT journal article T1 Counting the ideals with given genus of a numerical semigroup A1 Moreno Frías, María Ángeles A1 Rosales, José Carlos A2 Matemáticas K1 Numerical semigroup K1 ideal K1 I(S)-semigroup K1 Frobenius number K1 genus K1 multiplicity K1 genus K1 ordinary semigroup AB If S is a numerical semigroup, denote by g(S) the genus of S. A numerical semigroupT is an I(S)-semigroup if T\{0} is an ideal of S. If k ∈ N, then we denote by i(S, k)the number of I(S)-semigroups with genus g(S) + k. In this work, we conjecture thati(S, a) ≤ i(S, b) if a ≤ b, and we show that there is a term from which this sequencebecomes stationary. That is, there exists kS ∈ N such that i(S, kS) = i(S, kS + h)for all h ∈ N. Moreover, we prove that the conjecture is true for ordinary numericalsemigroups, that is, numerical semigroups which the form {0,m,→} for some positiveinteger. Additionally, we calculate the term from which the sequence becomes stationary. PB World Scientific Publishing Company SN 0219-4988 YR 2023 FD 2023 LK http://hdl.handle.net/10498/35496 UL http://hdl.handle.net/10498/35496 LA eng DS Repositorio Institucional de la Universidad de Cádiz RD 10-may-2026