Positive divisors
Source: Indonesia Mathematics Olympiad 2007 Day 1 Problem 2
June 2, 2008
number theoryrelatively primeDiophantine equationnumber theory proposed
Problem Statement
For every positive integer , denote the number of positive divisors of and denote the sum of all positive divisors of . For example, b(14)\equal{}4 and p(14)\equal{}24. Let be a positive integer greater than .
(a) Prove that there are infinitely many positive integers which satisfy b(n)\equal{}k^2\minus{}k\plus{}1.
(b) Prove that there are finitely many positive integers which satisfy p(n)\equal{}k^2\minus{}k\plus{}1.