title: "IMO 1987 LL TUR63"
description: "Compute 2n"
date: "2026-05-29T11:51:44+07:00"
tags: ["imo", "longlist", "mathematics", "olympiad"]
categories: ["mathematics"]
year: 1987
type: "longlist"
origin: "TUR"
weight: 198700063
draft: false
IMO 1987 LL TUR63
Origin: TUR
Problem
Compute 2n k=0(−1)ka2 k, where ak are the coefficients in the expansion (1 − \sqrt 2x + x2)n = 2n k=0 akxk.