A sequence {a_i} is said to be periodic with period p with if it satisfies a_i = a_(i + n p) for n = 1, 2, .... For example, {1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, ...} is a periodic sequence with least period 2.

eventually periodic | periodic function | periodic point