Arithmetic Sequence Calculator
Enter the first term (a₁), common difference (d), and the term number (n) to find the nth term, the sum of the first n terms, and a list of the first 10 terms.
Arithmetic Sequence Formulas
Frequently Asked Questions
An arithmetic sequence (or arithmetic progression) is a list of numbers where consecutive terms differ by a constant value called the common difference (d). Example: 2, 5, 8, 11… with d = 3.
Use the formula aₙ = a₁ + (n−1)d, where a₁ is the first term, d is the common difference, and n is the position.
Sₙ = n/2 × (2a₁ + (n−1)d). This formula sums the first n terms. It can also be written as Sₙ = n/2 × (first term + last term).
The common difference (d) is the fixed amount added (or subtracted) to get from one term to the next. For 3, 7, 11, 15 the common difference is 4.
Yes. A negative common difference creates a decreasing sequence. For example, 20, 15, 10, 5, 0, −5… has d = −5.