It is a function whose domain is the finite or infinte set.

What is the next term in the arithmetic sequence -2, -6, -10, -14, ...?

What is the leading coefficient of the polynomial function f(x) = 2x + x³ + 4?

What is an angle whose vertex is on a circle and whose sides contain chords of the circle?

It is an arrangement of things in a definite order or the ordered arrangement of distinguishable objects without allowing repetitions among the objects.