Number Sequence Calculator Online
Generate arithmetic, geometric and Fibonacci sequences, find the nth term, and add up the sum, right in your browser.
The Number Sequence Calculator runs entirely in your browser. The first term, difference or ratio, and term count you enter are computed locally and never leave your device.
Open the Factor Calculator
About Number Sequence Calculator
Number Sequence Calculator generates arithmetic, geometric, and Fibonacci-style sequences from a starting value and a common difference, ratio, or seed pair. Choose a sequence type, enter the first term and the common difference or ratio (or the first two terms for a Fibonacci sequence), and set how many terms to generate. The tool lists every term, works out the nth term with the matching formula, and adds up the running sum. It is useful for checking algebra and pre-calculus homework, building patterns for a lesson plan, or verifying a recursive formula before you code it. Everything runs locally in your browser, so the numbers you enter are never uploaded.
Features
- Generates arithmetic sequences from a first term and common difference
- Generates geometric sequences from a first term and common ratio
- Generates Fibonacci-style sequences from any two seed terms
- Calculates the nth term with the matching closed-form formula
- Adds up the sum of every generated term
- Supports negative and decimal first terms, differences, and ratios
- Caps very long sequences at a readable limit so the list stays usable
- Copy a plain-text summary of the sequence, nth term, and sum in one click
How to use the Number Sequence Calculator
- Pick a sequence type: Arithmetic, Geometric, or Fibonacci
- Enter the first term and the common difference, ratio, or second seed term
- Enter how many terms to generate
- Read the sequence, nth term, and sum, then copy the summary
Example
Input
arithmetic a=2 d=3, 5 terms
Output
2, 5, 8, 11, 14 (sum 40)
Each term adds the common difference 3 to the one before it: 2, 5, 8, 11, 14.
Common errors & troubleshooting
- The geometric sequence shows all zeros after the first term. — Check that the common ratio field isn't 0 — a ratio of 0 multiplies every term after the first down to zero.
- The Fibonacci sequence doesn't match the classic 0, 1, 1, 2, 3... — Set the first term to 0 and the second term to 1. The Fibonacci mode starts from whatever two seed values you enter, so different seeds produce a different (but still valid) Fibonacci-style sequence.
- Requesting a very large number of terms doesn't show all of them. — The list is capped at 100 terms so it stays readable — lower the term count if you need to see a specific later term, or use the nth-term result for that.
- The sum looks off for a geometric sequence with a big ratio. — Geometric sums grow fast — a ratio above 1 with many terms can reach very large numbers quickly, which is expected exponential growth, not a calculation error.
Frequently asked questions
- What does the Number Sequence Calculator do?
- It generates arithmetic, geometric, or Fibonacci-style number sequences from the values you enter, then shows every term, the nth term, and the sum of the sequence.
- How does the Number Sequence Calculator find the nth term of an arithmetic sequence?
- It uses the formula a + (n-1)d, where a is the first term, d is the common difference, and n is the term position you asked for.
- How does the Number Sequence Calculator find the nth term of a geometric sequence?
- It uses the formula a·r^(n-1), where a is the first term, r is the common ratio, and n is the term position.
- Can the Number Sequence Calculator start a Fibonacci sequence with custom seed values?
- Yes. Enter any first and second term and the calculator builds each later term as the sum of the two before it, so you can generate Fibonacci-style sequences beyond the classic 0, 1 seed.
- Is there a limit to how many terms the Number Sequence Calculator will list?
- Yes, the visible list is capped at 100 terms so it stays readable. The nth-term and sum results still reflect the number of terms you requested up to that cap.
- Does the Number Sequence Calculator send my numbers anywhere?
- No. The Number Sequence Calculator runs entirely in your browser. The values you type are computed locally and are never uploaded to ArrayKit.
Related tools
All ArrayKit tools