If we are talking about
for 10 bit down = 1024 pubkeys
for 20 bit down = 1024*1024 = 1048576 pubkeys
for 30 bit down = 1024*1024*1024 = 1073741824 pubkeys
then NotATether posted it several posts above:
https://gist.github.com/ZenulAbidin/286a652b160086b3b0f184a886ba68caIf we are talking about
1048576 and 1073741824 pubkeys with each other addition and mutiplication will return you 260 pubkeys apear where 16 pubkeys sure inside 10 bit down from main pubkey
these 260 pubkeys again played for get 30 bit down for 1/720 pubkeys
only Brainless knows this, it is his secret. I don't know if he told anyone about it