玲珑杯热身赛A--Alarm （找规律）

 

 

DESCRIPTION

Given a number sequence $[3,7,22,45,116,...][3,7,22,45,116,...].\; Please\; tell\; me\; the\; kk-th\; number.$

 

INPUT

A number $\mathrm{T (T<100)T (T<100)\; indicates\; the\; number\; of\; the\; input\; cases.\; Then\; for\; each\; case\; there\; only\; is\; one\; integer\; k (1\le k\le 10000)k (1\le k\le 10000).}$

 

OUTPUT

For each case, ouput the $\mathrm{kk-th\; number\; of\; the\; sequence\; in\; one\; line.}$

 

SAMPLE INPUT

2
1
4

 

SAMPLE OUTPUT

3
45

题意很简单，就是找规律，通过规律我们可以发现：

 

然后打表就可以过啦~  

#include <cstdio>
#include <cstring>
#include <iostream>
#include <cmath>
#include<algorithm>
using namespace std;

const int maxn=1000007;
const int INF=0x3f3f3f3f;

long long v[maxn], a[maxn], k;
void Isprime()
{
    memset(v, 0, sizeof(v));
    for(int i=2; i<maxn; i++)
    {
        if(v[i]==0)
        {
            a[k++]=i;

            for(int j=i+i; j<maxn; j+=i)
                v[j]=1;
        }
    }
}
int main()
{
    k=1;
    Isprime();

    int T;
    scanf("%d", &T);

    while(T--)
    {
        int n;
        scanf("%d", &n);
        printf("%lld\n", a[n]*a[n]-n);
    }
    return 0;
}