Which of the following progression is helpful to derive harmonic progression?

What is the value of the 21^st term of the harmonic progression:$\frac{1}{5}$ ,$\frac{1}{9}$ ,$\frac{1}{13}$ ,$\frac{1}{14}$ -...?

Find the fifth term of the harmonic progression 1/4, 1/7, 1/10….  

Compute the 16th term of HP if the 6th and 11th term of HP are 10 and 18, respectively.

1.    Determine whether the following sequence is harmonic: -1, 1/2, -1/3, 1/4, -1/5, ....

Is the sentence true or false ?

The terms of a harmonic progression is of the form, 1/a, 1/(a + d), 1/(a + 2d), 1/(a + 3d), 1/(a + 4d),...1/(a + (n - 1)d).

Fill in the blank:

If 6, 4, 3,… is the harmonic progression then 1/6, 1/4, 1/3,… is _________.

These are series who are reciprocals of an arithmetic series without 0 as one of its terms.

Determine the 8th term of the harmonic progression 6, 4, 3,…

Find the 12^th term of the harmonic progression, if the fifth term is 1/16, and the eighth term is 1/25.