MathDB
2020 PUMaC NT A8

Source:

January 1, 2022
number theory

Problem Statement

What is the smallest integer a0a_0 such that, for every positive integer nn, there exists a sequence of positive integers a0,a1,...,an1,ana_0, a_1, ..., a_{n-1}, a_n such that the first n1n-1 are all distinct, a0=ana_0 = a_n, and for 0in10 \le i \le n -1, aiai+1a_i^{a_{i+1}} ends in the digits 0ai\overline{0a_i} when expressed without leading zeros in base 1010.