June 2017 Fiendish Function

The Fiendish Function posed during June 2017 had the following sample guesses and replies:

• GUESS
• REPLY
• 1
• 4
• 2
• 16
• 3
• 256
• 4
• 66
• 5
• 12
• 10
• 8

The rule was: "Add 2 to the power of the number's digits together, then add 2 to the power of the digits together".

Suppose the guess was 17:

• Take the number's digits, giving 1, 7
• Take 2 to the power of each digit, giving 2, 128
• Add these together, giving 130.
• Take the number's digits, giving 1, 3, 0
• Take 2 to the power of each digit, giving 2, 8, 1
• Add these together, giving 11.

So the result is 11.