MathDB
Quadratic integers

Source: Romanian NO 2011, grade x, p.4

October 3, 2019
algebra

Problem Statement

a) Show that there exists exactly a sequence (xn,yn)n0 \left( x_n,y_n \right)_{n\ge 0} of pairs of nonnegative integers, that satisfy the property that (1+33)n=xn+yn33, \left( 1+\sqrt 33 \right)^n=x_n+y_n\sqrt 33, for all nonegative integers n. n.
b) Having in mind the sequence from a), prove that, for any natural prime p, p, at least one of the numbers yp1,yp y_{p-1} ,y_p and yp+1 y_{p+1} are divisible by p. p.