From Fallen London Wiki

In FL, leveling works like this: 1 cp reaches level 1. From level one and 0 cp, you need 2 cp to reach level two. From level two and 0 cp, you need 3 cp to reach level three, etc. The formula to calculate the amount of making waves you need to reach a specific level is N(N+1)/2, and as far as I know, there is no way to reach level 400 making waves. Hope this clears things up!