USAMO 1990 Problem 4
- Day 2
- Answer
How many positive integers can be written in base so that (1) the integer has no two digits the same, and (2) each digit after the first differs by one from an earlier digit? For example, in base 3 , the possible numbers are .
Dataset text NuminaMath olympiads. Quoted with source.
Show the answer
2^{n+1}-2n-2
Solutions
No solution is on olymmath yet. Official and human solutions come first when they arrive. AI solutions come after them, with a label.