An arithmetic progression or arithmetic sequence is a sequence of numbers such that the difference between the consecutive terms is constant. For instance, the sequence 5, 7, 9, 11, 13, 15, . . . is an arithmetic progression with a common difference of 2. If the initial term of an arithmetic progression is a₁ and the common difference of successive members is d, then the n-th term of the sequence (aₙ) is given by: aₙ=a₁+(n-1)d, and in general aₙ=aₘ+(n-m)d.
