Arithmetic Sequences

One of the beauties of arithmetic sequences is that if we know the first term (a1) and the common difference (d), then we can easily calculate the terms an and Sn for any n with the following formulas: an = a1 + d*(n - 1), where d is the common difference. Sn = n*(a1 + an)/2 We can use these formulas to derive more information about the sequence.