What is the 1st term of the harmonic sequence if the 10th term is 1/5 and the 20th term is 1/10

Answer 1

looking at the 2nd and 3rd terms, we see that the value is divided by 2 in 10 steps. If this is a geometric progression that means that each step is a division by 2^(1/10)

Going from the 10th term backwards to the first is 9 steps, so the 2nd term will be multiplied by (2^(1/10))⁹ , which is 2^(9/10)

PS : each step is 2^0.1 = 1.07177

multiply or divide depending on which way you are going