`
suoyihen
  • 浏览: 1352233 次
文章分类
社区版块
存档分类
最新评论

POJ 3006 Dirichlet's Theorem on Arithmetic Progressions 素数的判断 筛选法

 
阅读更多

http://poj.org/problem?id=3006

Dirichlet's Theorem on Arithmetic Progressions
Time Limit:1000MS Memory Limit:65536K



Description

Ifaanddare relatively prime positive integers, the arithmetic sequence beginning withaand increasing byd, i.e.,a,a+d,a+ 2d,a+ 3d,a+ 4d, ..., contains infinitely many prime numbers. This fact is known as Dirichlet's Theorem on Arithmetic Progressions, which had been conjectured by Johann Carl Friedrich Gauss (1777 - 1855) and was proved by Johann Peter Gustav Lejeune Dirichlet (1805 - 1859) in 1837.

For example, the arithmetic sequence beginning with 2 and increasing by 3, i.e.,

2, 5, 8, 11, 14, 17, 20, 23, 26, 29, 32, 35, 38, 41, 44, 47, 50, 53, 56, 59, 62, 65, 68, 71, 74, 77, 80, 83, 86, 89, 92, 95, 98, ... ,

contains infinitely many prime numbers

2, 5, 11, 17, 23, 29, 41, 47, 53, 59, 71, 83, 89, ... .

Your mission, should you decide to accept it, is to write a program to find thenth prime number in this arithmetic sequence for given positive integersa,d, andn.

Input

The input is a sequence of datasets. A dataset is a line containing three positive integersa,d, andnseparated by a space.aanddare relatively prime. You may assumea<= 9307,d<= 346, andn<= 210.

The end of the input is indicated by a line containing three zeros separated by a space. It is not a dataset.

Output

The output should be composed of as many lines as the number of the input datasets. Each line should contain a single integer and should never contain extra characters.

The output integer corresponding to a dataseta,d,nshould be thenth prime number among those contained in the arithmetic sequence beginning withaand increasing byd.

FYI, it is known that the result is always less than 106(one million) under this input condition.

Sample Input

367 186 151
179 10 203
271 37 39
103 230 1
27 104 185
253 50 85
1 1 1
9075 337 210
307 24 79
331 221 177
259 170 40
269 58 102
0 0 0

Sample Output

92809
6709
12037
103
93523
14503
2
899429
5107
412717
22699
25673

分享到:
评论

相关推荐

Global site tag (gtag.js) - Google Analytics