【欧拉函数】 HDOJ 4483 Lattice triangle

看网上的题解做的。。。。

#include <iostream>  
#include <queue>  
#include <stack>  
#include <map>  
#include <set>  
#include <bitset>  
#include <cstdio>  
#include <algorithm>  
#include <cstring>  
#include <climits>  
#include <cstdlib>
#include <cmath>
#include <time.h>
#define maxn 100005
#define maxm 40005
#define eps 1e-10
//#define mod 1000000007
#define INF 999999999
#define lowbit(x) (x&(-x))
#define mp mark_pair
#define ls o<<1
#define rs o<<1 | 1
#define lson o<<1, L, mid  
#define rson o<<1 | 1, mid+1, R  
typedef long long LL;
//typedef int LL;
using namespace std;
//LL powmod(LL a, LL b){LL res=1,base=a;while(b){if(b%2)res=res*base%mod;base=base*base%mod;b/=2;}return res;}
void scanf(int &__x){__x=0;char __ch=getchar();while(__ch==' '||__ch=='\n')__ch=getchar();while(__ch>='0'&&__ch<='9')__x=__x*10+__ch-'0',__ch = getchar();}
LL gcd(LL _a, LL _b){if(!_b) return _a;else return gcd(_b, _a%_b);}
// head

LL phi[maxn];
LL a[maxn], b[maxn], c[maxn];
LL n;
const LL  mod = 1000000007, md = (LL) mod * 6;
void init(void)
{
	phi[1] = a[1] = c[1] = 1, b[1] = 2;
	for(int i = 2; i < maxn; i++) if(!phi[i])
		for(int j = i; j < maxn; j += i) {
			if(!phi[j]) phi[j] = j;
			phi[j] -= phi[j]/i;
		}
	for(int i = 2; i < maxn; i++) {
		a[i] = (a[i-1] + phi[i] * 2) % mod;
		b[i] = (b[i-1] + phi[i] * i * 3) % mod;
		c[i] = (c[i-1] + phi[i] * i % mod * i % mod) % mod;
	}
}
int main(void)
{
	int _;
	init();
	while(scanf("%d", &_)!=EOF) {
		while(_--) {
			scanf("%I64d", &n), n++;
			LL tmp = n * n % mod, ans = 0;
			ans = tmp * (tmp-1) % md * (tmp-2) % md / 6;
			ans -= tmp * (n-1) % md * (n-2) * 2 % md / 6;
			tmp = 0;
			for(LL k = 2; k < n; k++) {
				LL m = (n-1)/k;
				tmp = (tmp + (LL)(k-1) * (a[m] % mod * n % mod * n % mod - (LL)n * k % mod * b[m] % mod + (LL)k * k % mod * c[m] % mod))%mod;
			}
			ans -= tmp*2;
			printf("%I64d\n", (ans % mod + mod) % mod);
		}
	}
	return 0;
}