These are a few topics that are taught in the Ontario curriculum as specified a the Ontario Ministry of Education. As all secondary school teachers are professionals, it would be absolutely impossible that any of them would even consider not teaching concepts such as arithmetic and geometric sequences, which form the overall majority of Section C, Discrete Functions, in one of four sections for Grade 11 Mathematics. Consequently, the only reasonable explanation that so many university students claim never to have seen arithmetic or geometric sequences is that they have simply forgotten what they learned in Grade 11.
In the course Functions, Grade 11, University Preparation, MCR3U, there are only four topics required:
Thus, fully one quarter of Grade 11 mathematics should cover arithmetic and geometric sequences.
If you forgot this information, these tutorials will help refresh your memories: