\vdots

Vertical dots, often used to indicate continuation in a vertical list or matrix.

Examples

Indicating continuation in a matrix column.

\begin{bmatrix} a & b \\ \vdots & \vdots \\ x & y \end{bmatrix}

Indicating continuation in a sequence.

1, 2, \vdots, n

Indicating continuation in a list of functions.

f_1, f_2, \vdots, f_n