The sequence of triangle numbers is generated by adding the natural numbers. So the 7th triangle number would be 1 + 2 + 3 + 4 + 5 + 6 + 7 = 28. The first ten terms would be:
1, 3, 6, 10, 15, 21, 28, 36, 45, 55, ...
Let us list the factors of the first seven triangle numbers:
1: 1
3: 1,3
6: 1,2,3,6
10: 1,2,5,10
15: 1,3,5,15
21: 1,3,7,21
28: 1,2,4,7,14,28
We can see that 28 is the first triangle number to have over five divisors.
What is the value of the first triangle number to have over five hundred divisors?
求第一个有超过500个除数的三角数。
观察：每个三角数除以前半部分的除数，等于后半部分的除数。
from math import sqrtimport timestart=time.time()now=2num=1while True: num=num+now now+=1 t=0 for x in range(1,int(sqrt(num))+1): if num%x==0: t+=2 if sqrt(num)==int(sqrt(num)): t=t-1 if t>500: break print num原文：http://www.cnblogs.com/lwjl/p/4275733.html