Like to create a table with a particular column is always sorted

I like to create a table, with columns Entity_id, seq_nbr, amount, description.

I want the column seq_nbr in sorted manner, whenever date is inserted in the table it should be sorted automatically.If that column is declared as primary key. i can able to achieve it. But i don't want that as primary key. it should allow duplicate values. kindly help me with the solution.

Thanks