Algebra is the discipline of pure mathematics that is concerned with the study of the abstract properties of a set, once this is endowed with one or more operations that respect certain rules (axioms) ...

Algebra can be used to show the properties of expressions and demonstrate when different expressions are equivalent. Rules can be used that apply to sets of numbers, such as odd numbers and even ...

The first term is in position 1, the second term is in position 2 and so on. Position to term rules use algebra to work out what number is in a sequence if the position in the sequence is known.