This site is supported by donations to The OEIS Foundation.



(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A286676 Numerators of the Nash equilibrium of guesses for the number guessing game for n numbers. 1
1, 3, 9, 2, 20, 12, 23, 27, 31, 35, 187, 1461, 485, 105, 64, 69 (list; graph; refs; listen; history; text; internal format)



Consider two players: one player picks a number between 1-N, and another player guesses numbers, receiving feedback "too high" or "too low". The number picker is trying to maximize the expected number of guesses, whereas the number guesser is trying to minimize the expected number of guesses. While a binary search would in expectation be the optimal strategy if the number was chosen randomly, it is not the case if the number is chosen adversarially.


Table of n, a(n) for n=1..16.

Michal Forisek, Candy for each guess, p. 15-19, IPSC 2011 booklet.

Michal Forisek, Candy for each guess


For n=3, the Nash equilibrium of guesses is 9/5. This is attained when the number picker chooses 1 with 2/5 probability, 2 with 1/5 probability, and 3 with 2/5 probability. The number guesser guesses the numbers 0,2,1 in order with 1/5 probability, 2,0,1 in order with 1/5 probability, and 1,0,2 (i.e. binary search) with 3/5 probability.


For denominators see A286677.

Sequence in context: A263559 A262343 A140985 * A246379 A303941 A176885

Adjacent sequences:  A286673 A286674 A286675 * A286677 A286678 A286679




Lewis Chen, May 12 2017



Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 20 22:44 EDT 2019. Contains 328291 sequences. (Running on oeis4.)