How do I set a start value for 'serial' or sequence in psql

Hi everyone,

I have a migration like this:

def change
    add_column :orders, :order_number, :serial
end

and when I create a new record in the database I get 1,2,3 etc.,
What I need is to set a start value like 1000 and auto increment to 1001, 1002,.. etc.,