You should technically eliminate the 2^0 condition - I'd like to receive 1 point for every tube I didn't hang on the rack. Woo 21 points (18 ringers and 3 keepers) if I do nothing! Kinda like bonus objects in FLL!
I kid.
Also. you should eliminate the "+2 points per Singleton" statement. Unlike in the Triple Play game, you do not get points for individual tubes hung on the rack. Your points are solely derived from the size of the horizontal and vertical rows you create. A row of 1 Singleton is covered by your 2^x scoring statement.
Some people don't automatically know that 2^5 = 32 etc. You may wish to provide a compact scoring table to go along with your statement.
Thanks for providing this!