There exists a quadratic sequence with a_0 = 0, a_n = 1996
Source: IMO Shortlist 1996, N3
August 9, 2008
number theoryInteger sequencePerfect SquaresExtremal combinatoricsrecurrence relationIMO Shortlist
Problem Statement
A finite sequence of integers is called quadratic if for each in the set we have the equality |a_i \minus{} a_{i\minus{}1}| \equal{} i^2.
a.) Prove that any two integers and there exists a natural number and a quadratic sequence with a_0 \equal{} b and a_n \equal{} c.
b.) Find the smallest natural number for which there exists a quadratic sequence with a_0 \equal{} 0 and a_n \equal{} 1996.