题目

On Saturday my Catalan friend invited me to come along to a Calotada. Being from the UK, I had no idea what this would need, but he promised me it was a fun Catalan (卡塔兰) tradition, and so I agreed to go. I wasn’t disappointed! First, we took a train out to a Small town near Tarragona, about an hour away from Barcelona centre. I was already amazed by how different everything looked from the city as the train rushed through small towns, all sitting on the coastline. When we arrived, we were greeted by the sight of a small wind instrument band and about a dozen people dancing in a数列{an}满足a1=1，，则a10=    ．