MathDB
Three sequences have a simultaneous relation

Source: 1961 All-Soviet Union Olympiad

August 4, 2015
algebraSequences

Problem Statement

Prove that for any three infinite sequences of natural numbers (an)n1(a_n)_{n\ge 1}, (bn)n1(b_n)_{n\ge 1}, (cn)n1(c_n)_{n\ge 1}, there exist numbers pp and qq such that apaqa_p\ge a_q, bpbqb_p\ge b_q and cpcqc_p\ge c_q.