# Category: Series and Sequences

## Sequences

In simple words sequence is a list of numbers written in definite order: `a_1,a_2,...,a_n`. `a_1` is first term, `a_2` is second term, and, in general, `a_n` is n-th term. We deal with infinite sequences, so each term `a_n` will have a successor `a_(n+1)`.