Many options for off-campus courses in mathematics are available at Utrecht University. Many of these courses are taught in Dutch, but some in English. Coursework at University College Utrecht often does not align exactly the intended prerequisites within University Utrecht Mathematics Bachelor, but in many cases this can be resolved with a little additional reading and/or instructor permission.
The following courses can be said to build on UCSCIMAT11 (which is arguably a bare minimum prerequisite, although additional preparatory coursework is sometimes preferable): WISB121 Linear algebra (some overlap with UCSCIMAT11 and other UCU courses), WISB137 Calculus B, WISB141 Introduction geometry, WISB152 Computer programming for Mathematics, WISB231 Differential equations (some overlap with UCSCIMAT11 and other UCU courses), WISB251 Numerical analysis, WISB272 Game theory, WISB382 History of mathematics.
The following courses are natural follow-ups to UCSCIMAT14 (a bare minimum prerequisite; often more preparatory coursework is preferable): WISB114 Analysis (some overlap with UCSCIMAT31), WISB243 Introduction to topology, WISB321 Basic number theory, INFOB3DW Discrete mathematics.
WISB211 Functions and series can be seen as a more theoretical follow-up or companion course to UCSCIMAT21. BETA-B1CS Introduction to complex systems can be a follow-up course to UCSCIMAT22.
WISB221 Group theory is an extended version of UCSCIMATL3, and WISB222 Rings and Galois theory is a natural follow-up course to this. WISB161 Introduction probability theory and statistics is an extended version of UCSCIMATL4.
WISB311 Complex analysis may also be suitable for advanced students. Students combining mathematics with economics may want to consider WISB377 Econometrics and WISB373 Introduction to financial mathematics.