2040.lean:3:8-3:13: error: failed to synthesize instance
  HPow Nat Nat Int
2040.lean:9:8-9:13: error: failed to synthesize instance
  HPow Nat Nat Int
2040.lean:15:8-15:13: error: failed to synthesize instance
  HPow Nat Nat Int
2040.lean:13:2-15:22: error: type mismatch
  trans (sorryAx (a = 37)) (sorryAx (37 = 2 ^ n))
has type
  a = @OfNat.ofNat Nat 2 (instOfNatNat 2) ^ n : Prop
but is expected to have type
  a = @OfNat.ofNat Int 2 instOfNatInt ^ n : Prop