exercism fetch csharp nth-prime

Nth Prime

Given a number n, determine what the nth prime is.

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

If your language provides methods in the standard library to deal with prime numbers, pretend they don't exist and implement them yourself.


For this exercise the following C# feature comes in handy: Enumerables are evaluated lazily. They allow you to work with an infinite sequence of values. See this article.

Note: to help speedup calculation, you should not check numbers which you know beforehand will never be prime. For more information, see the Sieve of Eratosthenes.


A variation on Problem 7 at Project Euler http://projecteuler.net/problem=7

Submitting Incomplete Solutions

It's possible to submit an incomplete solution so you can see how others have completed the exercise.