# Any alphebet with a small n?

1. Jan 14, 2006

### teng125

any alphebet with a small n??

does snybody knowswat is the meaning of the eqn when there is any alphebet with a small n underneath or next to it?

2. Jan 14, 2006

### arildno

1. Please write in English, and not in Gibberish
2. What are you asking about? Indices like in $a_{n}$?

3. Jan 14, 2006

### teng125

yaya...that's what i mean

4. Jan 14, 2006

### HallsofIvy

Arildno, there are an awful lot of people here for whom English is a difficult language! Cut them a little slack.

teng125, and alphabetical character (to make arildno happy) with a subscript n, normally, is just a way 9f distinguishing among many different values. One application is with vectors where we may label the "x","y", and "z" components of the vector a by a1, a2, a3.

Another important application, which is likely to be what you are looking at, is to label numbers in sequences. The only difference between a sequence and a function is that the "domain" of a sequence is the positive integers: 1,2, 3, etc. A standard way to distinguish them is to use x for a "real variable" and n for a "positive integer variable". Some texts actually use a(n) for a sequence (more correctly the nth term in the sequence) but it is more traditional to use a subscript: an.