About the Arithmetic Sequence Calculator
Find the nth term, the sum of the first n terms and list an arithmetic sequence from its first term and common difference.
Also known as: arithmetic progression, ap calculator, nth term arithmetic, arithmetic series sum.
How to use this calculator
- Enter first term (a₁), common difference (d), number of terms (n).
- The result updates instantly as you type — press Calculate (or Enter) at any time.
- Open “Step-by-step” to see how the answer was worked out.
- Use Copy result or Share to save the answer or send a link with your inputs.
Formula
aₙ = a₁ + (n − 1)d · Sₙ = n/2 × (a₁ + aₙ)
Worked example
Using the values pre-filled in the calculator above:
- First term (a₁) = 3
- Common difference (d) = 4
- Number of terms (n) = 10
the calculator returns:
- a10: 39
- Sum of 10 terms: 210
- Sequence: 3, 7, 11, 15, 19, 23, 27, 31, 35, 39
Working
aₙ = 3 + (10 − 1) × 4 = 39Sₙ = 10/2 × (3 + 39) = 210