As a supplement we recommend some additional mathematical background in the book Data Structures and algorithms in Java, by M.T. Goodrich and R. Tamassia. In Danish there is a book called "Grundlæggende matematik for dataloger" which are used at DTU, it might be useful as well. The two books has not been read thoroughly by the teachers, but at first look they seems to be good. There is also a list of math books for the conoisseur.