After doing some work trying to figure out the PP progression on the Psion, I'm pretty sure that the chosen progression is [email protected]#$ numbers that got pulled out of someone's behind. After talking numbers over with someone who is much better at them than me, we determined that each level of progression gains you a random increase in PP over the previous level of one to two power points, plus however much the level increase from last time was. Here, have a table so you understand what I mean.

Level PP Total PP Gain Increase Over Last Level
1 2 +2 +2
2 6 +4 +2
3 11 +5 +1
4 17 +6 +1
5 25 +8 +2
6 35 +10 +2
7 46 +11 +1
8 58 +12 +1
9 72 +14 +2
10 88 +16 +2
11 106 +18 +2
12 126 +20 +2
13 147 +21 +1
14 170 +23 +2
15 195 +25 +2
16 221 +26 +1
17 250 +29 +3
18 280 +30 +1
19 311 +31 +1
20 343 +32 +1

As you can see, there is little if any pattern in this. There's even a single random +3 increase over the previous level's increase at level 17, for no obvious reason! With a little bit of work, I tweaked things a bit, and made the progression standardized, as shown on the following table.

Level PP Total PP Gain Increase Over Last Level
1 3 +3 +3
2 8 +5 +2
3 14 +6 +1
4 22 +8 +2
5 31 +9 +1
6 42 +11 +2
7 54 +12 +1
8 68 +14 +2
9 83 +15 +1
10 100 +17 +2
11 118 +18 +1
12 138 +20 +2
13 159 +21 +1
14 182 +23 +2
15 206 +24 +1
16 232 +26 +2
17 259 +27 +1
18 288 +29 +2
19 318 +30 +1
20 350 +32 +2

In general, changing the progression to a standardized increasing progression like this gives you around 6-8 more PP, the exact amount varying by level. The biggest benefit of this change, however, is that it now scales beyond level 20. I don't know exactly how well it will work, but epic psions will be a thing in a campaign I'm running, and this will give me exact PP pools for them. These changes can also be applied to any class that gains full ML progression, such as the Wilder and the Vitalist, thus letting their progression go beyond level 20 as well. I'll need to crunch numbers on partial manifesters to see how they need to be altered as well. I'll post the numbers here when I do.

Does anyone see anything wrong with the numbers as I've laid them out here, either in a way that would break the game, or any math mistakes I may have done?