MathDB

1

Part of 2018 USAJMO

Problems(1)

Digit switching

Source: 2018 USAJMO #1

4/18/2018
For each positive integer nn, find the number of nn-digit positive integers that satisfy both of the following conditions:
[*] no two consecutive digits are equal, and [*] the last digit is a prime.
USAJMO2018 USAJMO Problem 1