Find the following sum: 1+2+4+8+...+2^k-1

Question

I need help finding the terms before 2^k-1

Answer 1

Each term is twice the previous term:

 

1 + 2 + 4 + 8 + 16 + 32 + 64 + 128 + ....

 

Or each term is a power of 2

 

2⁰ + 2¹ + 2² + 2³ + 2⁴ + 2⁵ + 2⁶ + ...