April 2018 Fiendish Function

The Fiendish Function posed during April 2018 had the following sample guesses and replies:

  • GUESS
  • REPLY
  • 1
  • 1
  • 2
  • -4
  • 3
  • -19
  • 4
  • -48
  • 5
  • -93
  • 10
  • 24

The rule was: "Cube the number, then subtract from two to the power of the number".

Suppose the guess was 11:

  • Cube the number, giving 1331.
  • Calculate two to the power of the number, giving 2048.
  • Subtract the number from this, giving 717.

So the result is 717.