In mathematics, an index is a superscript or subscript to a symbol. Superscript indices are often, but not always, used to indicate powers. Subscript indices are usually used to label a set or sequence of variables. See also index set and family (mathematics). Wikibooks Wikiversity has more about this subject: School of Mathematics Wikiquote has a collection of quotations related to: Mathematics Look up Mathematics on Wiktionary, the free dictionary Wikimedia Commons has more media related to: Mathematics Bogomolny, Alexander: Interactive Mathematics Miscellany and Puzzles. ... A superscript is a number, figure, or symbol that appears above the normal line of type. ... A subscript is a number, figure or indicator, that appears below the normal line of type, when used in a formula, mathematical expression or description of a chemical compound. ... In mathematics, exponentiation is a process generalized from repeated (or iterated) multiplication, in much the same way that multiplication is a process generalized from repeated addition. ... In mathematics, an index set is another name for a function domain. ... In mathematics, an index set is another name for a function domain. ...

The index of a subgroup is the number of its left cosets (which is equal to the number of its right cosets). In mathematics, if G is a group, H a subgroup of G, and g an element of G, then gH = { gh : h an element of H } is a left coset of H in G, and Hg = { hg : h an element of H } is a right coset of H in G... In mathematics, if G is a group, H a subgroup of G, and g an element of G, then gH = { gh : h an element of H } is a left coset of H in G, and Hg = { hg : h an element of H } is a right coset of H in G...

The index of a Fredholm operator is the dimension of its kernel minus the dimension of its cokernel. In mathematics, a Fredholm operator is a bounded linear operator between two Banach spaces whose range is closed and whose kernel and cokernel are finite-dimensional. ... In the various branches of mathematics that fall under the heading of abstract algebra, the kernel of a homomorphism measures the degree to which the homomorphism fails to be injective. ... In abstract algebra, the cokernel of a homomorphism f : X → Y is the quotient of Y by the image of f. ...

The index of a real quadratic form Q is defined (but not always consistently) as p − q where Q can be written as a difference of p squared linear terms and q squared linear terms. In mathematics, a quadratic form is a homogeneous polynomial of degree two in a number of variables. ...

You can notice Pascal's Triangle:

 1 1 1 1 2 1 1 3 3 1 

1 4 6 4 1