By listing the first six prime numbers: 2, 3, 5, 7, 11, and 13, we can see that the 6th prime is 13.

What is the 10001st prime number?

Permalink: http://projecteuler.net/problem=7

It’s also pretty clear problem to make you more familiar with prime numbers.
As I said in Clojure Euler: Problem 003,
big amount of Project Euler problems devoted to prime numbers so it is **MUST HAVE** (*I don’t like this phrase either*)

You need to implement by yourself effective prime number algorithm. And only after that use one from library. As we do.

```
(:use [clojure.contrib.lazy-seqs :only (primes)])
```

This line import just one symbol `primes`

to your namespace. It’s a prime numbers lazy sequence. Lazy sequences briefly covered
in Clojure Euler: Problem 002 or Wikipedia article,
that’s enough for now.

Return to question.

What is the 10001st prime number?

No problem.

```
(last (take 10001 primes))
```

Two lines of code: one for import, one for solution. What can be simpler?

Note, that last return last element of the sequence and works in linear time.

Another one problem solved in few ~~seconds~~ minutes.

**P.S.** Actually, I lied. In linked solution I use 6 lines of code: namespace declaration, use, *empty line*,
comment with executing time, function declaration and, finally, solution.