I need work to be done in microsoft excel

I want to insert numbers, one by one and after inserting for example 24 numbers i want excel to show me the missing numbers from those 24 numbers excuding the doubles that i inserted...everytime i insert a new number excel must show me the missing numbers from the sequence that i inserted. Ex
Last 24 numbers :
1 4 4 5 7 7 9 12 12 15 17 19 19 22 22 25 28 30 30 32 33 34 35 35
Missing numbers
2 3 6 8 10 11 13 14 16 18 20 21 23 24 26 27 29 31