More on Progressions

Harmonic Progressions, HP
$h_n = \dfrac{n}{a_1 + (n - 1)d}$
 

Infinite Geometric Progression, IGP
$S = \dfrac{a_1}{1 - r}$
 

Arithmetic Mean
$\displaystyle AM = \dfrac{1}{n} \sum_{i = 1}^n \left( a_i \right)$
 

Harmonic Mean
$HM = \dfrac{n}{\displaystyle{\sum_{i = 1}^n} \left( \dfrac{1}{a_i} \right)}$
 

Geometric Mean
$\displaystyle GM = \left[ \prod_{i = 1}^n \left( a_i \right) \right]^{1/n}$