Define a 1-indexed sequence as follows:

* `A083569(1) = 1`
* `A083569(n)` where `n` is an integer greater than `1`, is the smallest integer m not occurring earlier such that `m+n` is a prime number.

Your task is to take in `n` and return `A083569(n)`.

```
 n  A083569(n)
 1  1
 2  3
 3  2
 4  7
 5  6
 6  5
 7  4
 8  9
 9  8
10 13
11 12
12 11
13 10
14 15
15 14
16 21
17 20
18 19
19 18
20 17

```

More testcases can be found [here](https://oeis.org/A083569/b083569.txt). The original sequence on OEIS can be found [here](https://oeis.org/A083569).

This is [code-golf](/questions/tagged/code-golf "show questions tagged 'code-golf'"). Shortest answer in bytes wins. [Standard loopholes](https://codegolf.meta.stackexchange.com/questions/1061/loopholes-that-are-forbidden-by-default) apply.