MathDB
A sequence

Source: Indian RMO 1997 Problem 2

October 26, 2005
number theorygreatest common divisor

Problem Statement

For each positive integer nn , define an=20+n2a_n = 20 + n^2 and dn=gcd(an,an+1)d_n = gcd(a_n, a_{n+1}). Find the set of all values that are taken by dnd_n and show by examples that each of these values is attained.
Back to ProblemsView on AoPS