Sequences
A finite sequence, or a string, of elements of a set S is a function from
{1,2,…, n} to S. The number n is called the length of this string.
An infinite sequence of elements of S is a function from {1,2,3,…}
We use the notation an to denote the image of the integer n, or the nth
term of the sequence. The sequence itself can be denoted by {an}.
Example. Consider the sequence {an}, where an=3n.
Then the list of terms of this sequence, namely,