Sequence Calculator

Calculate any term and the sum of an arithmetic or geometric sequence, choosing the type you need in one place.

  • Free to use
  • Accurate results
  • No registration required
  • Works on all devices
Choose arithmetic or geometric, then enter the first term, common difference/ratio, and term number to calculate the nth term and the sum of the first n terms.
Sequence type
For an arithmetic sequence, the amount added each time. For a geometric sequence, the factor multiplied each time.

Your result

29

nth term

Sum of first n terms155

AI explanation

Formula

Arithmetic: nth term = a₁ + (n−1)d. Geometric: nth term = a₁ × r^(n−1). Sum formulas follow accordingly.

Worked example

Arithmetic: 2, 5, 8, 11, ... find the 10th term

Worked example: Arithmetic: 2, 5, 8, 11, ... find the 10th term
FieldValue
Sequence typearithmetic
First term (a₁)2
Common difference (arithmetic) or common ratio (geometric)3
Term number (n)10
nth term29
Sum of first n terms155

Assumptions

  • For a geometric sequence, the first term cannot be zero.

Frequently asked questions

How do I know if my sequence is arithmetic or geometric?

An arithmetic sequence has a constant difference between consecutive terms (added each time). A geometric sequence has a constant ratio between consecutive terms (multiplied each time). If you have a list of numbers and want to find out which type it is, use the Number Sequence Calculator instead.

Why is there just one "common value" field?

It represents the common difference for an arithmetic sequence or the common ratio for a geometric sequence — whichever type you select above.

Are there dedicated calculators for each type?

Yes — the Arithmetic Sequence Calculator and Geometric Sequence Calculator offer the same math with type-specific labeling and examples.

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