Return list of unique account numbers

If I have two column list with the first column with names of say suppliers and the second column is a list of account numbers. Now a supplier can have more than one account numbers and I want to put in a formula where I put the name of the supplier in and then get a return of all the account numbers that the suppliers has.

Which function would I use for this?

Thanks, Would that be the easiest choice?

Try a Pivot Table.

Thanks for the help. Appreciate it.