MathDB
Infinite sequence

Source: ToT 2019

December 25, 2019
algebranumber theoryKvant

Problem Statement

Consider the following sequence of positive real numbers <a2<a1<a0<a1<a2<\dots<a_{-2}<a_{-1}<a_0<a_1<a_2<\dots infinite in both directions. For each positive integer kk let bkb_k be the least integer such that the ratio between the sum of kk consecutive terms and the greatest of these kk terms is less than or equal to bkb_k(This fact occurs for any sequence of kk consecutive numbers). Prove that the sequence b1,b2,b3,...b_1,b_2,b_3,... coincides with the sequence 1,2,3,...1,2,3,... or is eventually constant.