Question

How many increasing 3 term geometric progressions can be obtained from the sequence 1,2,2²,2³,... ..., 2ⁿ ?

Answer 1

Multiply with 2.

Answer 2

2^4;2^5;2^6...

Answer 3

Actually, the number of sets of 3-term geometric progression is required. For example, \[\left\{ 2 ^{2}, 2^{5},2^{8} \right\}\] is a three term geometric progression for n>=8