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# Well-known Sequences

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## Well-known Sequences

Below are some of the most common sequences. It is useful to be familier with these and their formulae.

* Even numbers *2, 4, 6, 8, 10, ...

**nth term = 2n**

* Odd Numbers* 1, 3, 5, 7, 9, ...

**nth term = 2n - 1**

* Square Numbers * 1, 4, 9, 16, 25, ...

**nth term = n**

^{2}* Cube Numbers * 1, 8, 27, 64, 125, ...

**nth term = n**

^{3}* Triangle Numbers * 1, 3, 6, 10, 15, ...

**nth term = ½ n (n + 1)**

* Prime Numbers * 2, 3, 5, 7, 11, 13, etc.

**No known formula!**

* Fibonacci Numbers* 1, 1, 2, 3, 5, 8, 13, ...

**Formula not needed for GCSE. Each term is found by adding the previous term!**

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