2 is the best solution, but it’s not the only solution, contrary to what Tom & Ray said.

Pick any number (> 2) of mangoes you want to end up with, subtract 1, multiply by 2. Repeat 7 times. This is the number of mangoes to start with.

For example if you want to end with 3, start with 130: 3, 4, 6, 10, 18, 34, 66, 130.