What is an arithmetic sequence?

In an arithmetic sequence, each term is obtained by adding or subtracting a constant or variable value to the previous term.
An arithmetic sequence is also called a linear sequence or a first-degree arithmetic sequence.
The formula to calculate the nth term of an arithmetic sequence is an = a1 + (n-1)r, where a1 is the first term and r is the common difference.
The sum of the terms of an arithmetic sequence can be calculated using the formula S = (n/2)(a1 + an), where S is the sum, n is the number of terms, a1 is the first term, and an is the nth term.