Problem 63 Powerful digit counts
Problem 63: Powerful digit counts
The 5-digit number, 16807=75, is also a fifth power. Similarly, the 9-digit number, 134217728=89, is a ninth power.
How many n-digit positive integers exist which are also an nth power?
分析
16807 是 5 位数,也是 7 的 5 次方
134217728 是 9[……]