文件名称：0~N中1的数目
文件大小：6KB
文件格式：TXT
更新时间：2016-03-31 15:50:06
0~N中1的数目
Consider a function which, for a given whole number n, returns the number of ones required when writing out all numbers between 0 and n. For example, f(13)=6. Notice that f(1)=1. What is the next largest n such that f(n)=n?