Nested Orderd List with combination of numbers, alphatets and roman numerals for numbering?

I want to create an ordered list that looks like this:

1. Item_1
2. Item_2:
    a. Subitem_1
    b. Subitem_2:
        I. Sub-Subitem_1
        II. Sub-Subitem_2
    c. Subtiem_3
3. Item 3

i.e. sub-lists should use alphabets/Roman Numbers or other such notations for numbering.

I tried nesting <ol> tags but that plainly numbered the sub-lists. Is there a way of doing this using only HTML?