tab-stop-list

tab-stop-list is a variable defined in `indent.el'.
Its value is

nil

• This variable is safe as a file local variable if its value
  satisfies the predicate `listp'.

Documentation:
List of tab stop positions used by `tab-to-tab-stop'.
This should be nil, or a list of integers, ordered from smallest to largest.
It implicitly extends to infinity through repetition of the last step.
For example, '(1 2 5) is equivalent to '(1 2 5 8 11 ...). If the list has
fewer than 2 elements, `tab-width' is used as the "last step".
A value of nil means a tab stop every `tab-width' columns.

You can customize this variable.

This variable was introduced, or its default value was changed, in version 24.4 of Emacs.