complete the pattern= 1,12,21,28,33,_,_
1 -> 12, increase of 11
12 -> 21, increase of 9
21 -> 28, increase of 7
28 -> 33, increase of 5
33 -> 36, increase of 3
36 -> 37, increase of 1.
1,12,21,28,33,36,37