MathDB
Sequence with primes - Argentina TST 2010

Source:

May 2, 2010
algebrapolynomialnumber theory unsolvednumber theory

Problem Statement

Let pp and qq be prime numbers. The sequence (xn)(x_n) is defined by x1=1x_1 = 1, x2=px_2 = p and xn+1=pxnqxn1x_{n+1} = px_n - qx_{n-1} for all n2n \geq 2. Given that there is some kk such that x3k=3x_{3k} = -3, find pp and qq.