Unless, in turn, you locate the index itself in pi at a much smaller index. And so on...
Find k candidate indices for your data, then locate each of them. If the smallest one is a significantly smaller index space, repeat.
It's recursive as well, you now need to store how many levels of indirection of indices you had to resolve, which will in turn take 20TB to store, unless you store that in pi as well, which in turn...
Can't tell if you're in on the joke or not, but for anyone who is genuinely wondering whether this might work: Consider that there are at most 256 different indexes that could be represented by a 1-byte index value, but if you're trying to store 9 bits of data, there are already 512 different possible things it could be that each need to be represented by a different index value, otherwise you won't be able to tell them apart. Those pigeons aren't gonna fit.
That’s what variable length encoding is for!