MathDB
Find the limit

Source: 2019 Jozsef Wildt International Math Competition-W. 8

May 18, 2020
limitSummationHarmonic NumbersSequencesgreatest integer funtion

Problem Statement

Let (an)n1(a_n)_{n\geq 1} be a positive real sequence given by an=k=1n1ka_n=\sum \limits_{k=1}^n \frac{1}{k}. Compute limne2ank=1n(k!2k+(k+1)!2(k+1))2\lim \limits_{n \to \infty}e^{-2a_n} \sum \limits_{k=1}^n \left \lfloor \left(\sqrt[2k]{k!}+\sqrt[2(k+1)]{(k+1)!}\right)^2 \right \rfloorwhere we denote by x\lfloor x\rfloor the integer part of xx.