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# The Weekly Challenge 168
You can find more information about this weeks, and previous weeks challenges at:
https://theweeklychallenge.org/
If you are not already doing the challenge - it is a good place to practise your
**perl** or **raku**. If it is not **perl** or **raku** you develop in - you can
submit solutions in whichever language you feel comfortable with.
You can find the solutions here on github at:
https://github.com/drbaggy/perlweeklychallenge-club/tree/master/challenge-168/james-smith
# Challenge 1 - Perrin Prime
***The Perrin sequence is defined to start with [3, 0, 2]; after that, term N is the sum of terms N-2 and N-3. (So it continues 3, 2, 5, 5, 7, ...) A Perrin prime is a number in the Perrin sequence which is also a prime number. Calculate the first 13 Perrin primes***
## Solution
Using our favourite is_prime library we loop through the Perrin numbers and checking to see if they are prime, if they are we display them - if not we restart the loop with `redo`.
Rather than keep the whole array we only need the last 3 numbers in the sequence to generate the next so we have: `$s -> $r`,
