Sequences, Progressions, Series, Means and Averages
Averages
Mean
For two numbers a and b,
Arithmetic Progression

An Arithmetic Progression (A. P.) with first term ‘a’ and Common Difference ‘d’ is given by: and n^{th }term,



Sum of first ‘n’ terms, Sn (First Term + Last Term)
Geometric Progression

A Geometric Progression (G. P.) with first term ‘a’ and Common Ratio ‘r’ is given by: ar2ar3n1where th term,



Harmonic Progression
Sum of Important Series

Sum of first n natural numbers:

Sum of the squares of the first n natural numbers:

Sum of the cubes of the first n natural numbers:
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