MathDB
Putnam 1954 A6

Source: Putnam 1954

July 17, 2022
PutnamSequencereal numbers

Problem Statement

Suppose that u0,u1,u_0 , u_1 ,\ldots is a sequence of real numbers such that un=k=1un+k2      for  n=0,1,2,u_n = \sum_{k=1}^{\infty} u_{n+k}^{2}\;\;\; \text{for} \; n=0,1,2,\ldots Prove that if un\sum u_n converges, then uk=0u_k=0 for all kk.