Beat the Primes
From Openwaterpedia
noun - Beat the Primes is a prime number based pool workout. This type of pool swimming set helps reinforce precise pace control.
Example
8 x 100 @ 1:30 where the athletes swim faster than a 1:23 pace for the first 100, swim faster than a 1:19 for the second 100, faster than a 1:17 for 3rd 100, faster than 1:13 for fourth 100, faster than a 1:11 for fifth 100, faster than a 1:07 for sixth 100, faster than a 1:05 for seventh 100, and faster than 1:03 for eighth 100. The intervals, pacing and distances can be approximately modified for each swimmer.