MathDB
Putnam 2002 B5

Source:

March 12, 2012
Putnamcollege contests

Problem Statement

A palindrome in base bb is a positive integer whose base-bb digits read the same backwards and forwards; for example, 20022002 is a 44-digit palindrome in base 1010. Note that 200200 is not a palindrome in base 1010, but it is a 33-digit palindrome: 242242 in base 99, and 404404 in base 77. Prove that there is an integer which is a 33-digit palindrome in base bb for at least 20022002 different values of bb.