Background
==========

A [super-prime](https://en.wikipedia.org/wiki/Super-prime) is a prime number whose index in the list of all primes is also prime. The sequence looks like this:

> 
> 3, 5, 11, 17, 31, 41, 59, 67, 83, 109, 127, 157, 179, 191, ...
> 
> 
> 

This is [sequence A006450 in the OEIS](https://oeis.org/A006450).

Challenge
=========

Given a positive integer, determine whether it is a super-prime.

Test Cases
==========

```

2: false
3: true
4: false
5: true
7: false
11: true
13: false
17: true
709: true
851: false
991: true

```

Scoring
=======

This is [code-golf](/questions/tagged/code-golf "show questions tagged 'code-golf'"), so the shortest answer in each language wins.