What is an arithmetic sequence?

A sequence where each term is obtained by adding a fixed number (common difference, d) to the previous term. Example: 2, 5, 8, 11, 14 — first term 2, common difference 3.

What is the formula for the nth term?

aₙ = a₁ + (n-1)d. The sum of n terms: Sₙ = n/2 × (a₁ + aₙ) = n/2 × (2a₁ + (n-1)d).

Arithmetic Sequence Calculator

Quick answer: Enter first term, common difference, and number of terms to find the nth term and sum.

Calculate any arithmetic sequence: find the nth term, partial sum, and list the first 20 terms. An arithmetic sequence has a constant difference between consecutive terms.

Last reviewed: April 2026Report an error

First Term (a₁)

Common Difference (d)

Number of Terms (n)

nth Term

19.00

a(10) = 19.00, sum = 100.00.

nth Term

19.00

Sum of n Terms

100.00

First 10 Terms

1.00, 3.00, 5.00, 7.00, 9.00, 11.00, 13.00, 15.00, 17.00, 19.00

How to Use This Arithmetic Sequence Calculator

1Enter the first term (a₁).
2Enter the common difference (d — can be negative).
3Enter the number of terms (n).
4Read the nth term, sum, and first 20 terms.

Frequently Asked Questions

: A sequence where each term is obtained by adding a fixed number (common difference, d) to the previous term. Example: 2, 5, 8, 11, 14 — first term 2, common difference 3.
: aₙ = a₁ + (n-1)d. The sum of n terms: Sₙ = n/2 × (a₁ + aₙ) = n/2 × (2a₁ + (n-1)d).

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Arithmetic Sequence Calculator

How to Use This Arithmetic Sequence Calculator

Frequently Asked Questions

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