This seems to work:
(2) + 2 + 4 + 8 + 16 + 32 +...= powers of two, the only question is how to translate this into a formula.
1. Find a series of consecutive integers such that the sum of the series is a power of 2.
2. If every term in a sequence S is defined by the sum of every item before it, give a formula for the nth term.
If I start with the first 2 terms being 1, then the next ones are just powers of 2 aren't they?