What is Arithmetic progression?
In [[mathematics]], an '''[[arithmetic]] progression''', or '''arithmetic sequence''', is a [[sequence]]. The difference between each two [[Term (mathematics)|terms]] which follow one another is always the same. This is different from a [[Geometry|geometric]] progression, where the [[ratio]] of change between two terms is constant. <br />If the initial term of an arithmetic progression is <math>a_1</math> and the common difference is <math>d</math>, then the <math>n</math>-th term of the sequence (<math>a_n</math>) is given by: :<math>a_n = a_1 + (n - 1)d</math> A finite portion of an arithmetic progression is called a '''finite arithmetic progression''' and sometimes just called an arithmetic progression. The [[summation|sum]] of a finite arithmetic progression is called an '''arithmetic series'''. {{Math-stub}} [[Category:Sequences and series]]