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CalcRiver

Number Sequence Calculator

Identify arithmetic, geometric, and Fibonacci sequences. Find the next terms, the N-th term, and the sum of a sequence automatically.

Separate numbers with commas or spaces.

Understanding Number Sequences

A number sequence is a list of numbers that follow a particular rule. This calculator helps you identify that rule and predict future numbers.

Arithmetic Sequences

In an arithmetic sequence, the difference between consecutive terms is constant.
Example: 2, 5, 8, 11 (Difference is +3).
Formula: aₙ = a₁ + (n-1)d

Geometric Sequences

In a geometric sequence, the ratio between consecutive terms is constant.
Example: 3, 6, 12, 24 (Ratio is ×2).
Formula: aₙ = a₁ × rⁿ⁻¹

Fibonacci Sequences

In a Fibonacci sequence, each number is the sum of the two preceding ones.
Example: 1, 1, 2, 3, 5, 8...

? Frequently Asked Questions

A sequence is a list of numbers in a specific order (e.g., 1, 2, 3). A series is the sum of the terms of a sequence (e.g., 1 + 2 + 3 = 6).

Use the 'Find N-th Term' tab. Enter the first term, the common difference (or ratio), and the position (N) you want to find.

This tool solves standard linear (arithmetic), exponential (geometric), and recursive addition (Fibonacci) patterns. It does not currently solve polynomial or quadratic sequences.