Discrete Math › Section E · Sequences › Topic E.1
Describing sequences and sums
Many counting questions have a different answer for every size n, and listing those answers in order gives a sequence. This topic sets out the two ways to pin a sequence down, a closed formula and a recursive definition, and the tools for adding up its terms.
In this topic
- One answer for every n
- Notation: terms and indices
- Closed formulas
- Recursive definitions
- Worked example: computing terms from a recurrence
- Worked example: a recurrence from a description
- Sequences worth recognising
- Partial sums and sigma notation
- Worked example: counting the steps of a loop
- The sequence of differences
- Common mistakes to avoid
- Key takeaways
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