A sequence is either a finite or infinite list of numbers which are called terms. One example of a sequence is The dots imply that the sequence continues infinitely. The terms are often represented as , and so on, where the numbers at the bottom right of the letters are called indices and specify the position of the terms in the sequence. In the example, Several terms can have the same value, even though this is not the case here. Two specific types of sequences are arithmetic sequences and geometric sequences.