Formulas at their prime

I was browsing at some formulae that yield prime numbers. But none of them actually always gave a prime number. Like (2^(2^n))-1 [2 to the power 2 to the power n whole minus 1]. But when n = 5, it gives out a composite number. So i was wondering is there a formula that always gives out a prime number?

Easy Math Editor

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Math	Appears as
Remember to wrap math in `$` ... `$` or `\[` ... `\]` to ensure proper formatting.
`2 \times 3`	$2 \times 3$
`2^{34}`	$2^{34}$
`a_{i-1}`	$a_{i-1}$
`\frac{2}{3}`	$\frac{2}{3}$
`\sqrt{2}`	$\sqrt{2}$
`\sum_{i=1}^3`	$\sum_{i=1}^3$
`\sin \theta`	$\sin \theta$
`\boxed{123}`	$\boxed{123}$

Comments

There isn't one.

Pi Han Goh - 1 year, 10 months ago

And can there be one? or is that impossible? why?

Jyothiraditya Datta Poduri - 1 year, 9 months ago

It is possible, but no one has found it yet.

Pi Han Goh - 1 year, 9 months ago

Math	Appears as
Remember to wrap math in `\(` ... `\)` or `\[` ... `\]` to ensure proper formatting.
`2 \times 3`	$2 \times 3$
`2^{34}`	$2^{34}$
`a_{i-1}`	$a_{i-1}$
`\frac{2}{3}`	$\frac{2}{3}$
`\sqrt{2}`	$\sqrt{2}$
`\sum_{i=1}^3`	$\sum_{i=1}^3$
`\sin \theta`	$\sin \theta$
`\boxed{123}`	$\boxed{123}$