MathDB
Professor D of some univeristy of Somewhere

Source: Balkan MO ShortList 2008 C1

April 5, 2020

Problem Statement

All n+3n+3 offices of University of Somewhere are numbered with numbers 0,1,2,,0,1,2, \ldots , n+1,n+1, n+2n+2 for some nNn \in \mathbb{N}. One day, Professor DD came up with a polynomial with real coefficients and power nn. Then, on the door of every office he wrote the value of that polynomial evaluated in the number assigned to that office. On the iith office, for ii \in {0,1,,n+1}\{0,1, \ldots, n+1 \} he wrote 2i2^i and on the (n+2)(n+2)th office he wrote 2n+22^{n+2} n3-n-3.
[*] Prove that Professor D made a calculation error [*] Assuming that Professor D made a calculation error, what is the smallest number of errors he made? Prove that in this case the errors are uniquely determined, find them and correct them.