PE 47(Distinct primes factors-Python数组)

Distinct primes factors

Problem 47

The first two consecutive numbers to have two distinct prime factors are:

14 = 2  7
15 = 3  5

The first three consecutive numbers to have three distinct prime factors are:

644 = 2²  7  23
645 = 3  5  43
646 = 2  17  19.

Find the first four consecutive integers to have four distinct prime factors. What is the first of these numbers?

Answer: 134043 Completed on Sat, 6 Apr 2013, 05:40

Go to the thread for problem 47 in the forum.

本题考察Python中数组的运用：

n=1000000
a=[0 for i in range(n+1)]
i=2
while i<=n:
    if (a[i]==0):
        j=2*i
        while j<n:
            a[j]=a[j]+1
            j+=i
    i+=1
for i in range(1,n+1-3):
    if (a[i]==4 and a[i+1]==4 and a[i+2]==4 and a[i+3]==4):
        print i