At first cut:
NFC: teams A (bye) BC/DE/FG, first round combinations: B with DF,DG,EF,EG (4). Now same with C gives another 4.
second round combinations: AB/CD gives A with C and D (2) plus same with B gives another 2.
Conf champ: AB gives 2.
so NFC gives 8*4*2=64, AFC gives 64 as well.
Super Bowl has possible 7 NFC, 7 AFC winners so 14*128 = 1792 different combinations.