Arithmetic Sequences

An arithmetic sequence has a constant difference between consecutive terms. If the difference is $d$, then each term equals the previous term plus $d$.

Example: $5, 8, 11, 14, 17, ...$ has $d = 3$. Each term is $3$ more than the last.

The general formula is $a_n = a_1 + (n - 1)d$ where $a_1$ is the first term and $d$ is the common difference. For our example, $a_n = 5 + (n - 1) \times 3 = 3n + 2$.