IMO 1984 LL GDR30
Decide whether it is possible to color the 1984 natural numbers
IMO 1984 LL GDR30
Origin: GDR
Problem
Decide whether it is possible to color the 1984 natural numbers 1, 2, 3, . . ., 1984 using 15 colors so that no geometric sequence of length 3 of the same color exists.