> For the complete documentation index, see [llms.txt](https://trizen.gitbook.io/sidef-lang/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://trizen.gitbook.io/sidef-lang/programming_tasks/w/wieferich_primes.md).

# Wieferich primes

```ruby
func is_wieferich_prime(p, base=2) {
    powmod(base, p-1, p**2) == 1
}

say ("Wieferich primes less than 5000: ", 5000.primes.grep(is_wieferich_prime))
```

## Output:

```
Wieferich primes less than 5000: [1093, 3511]
```