修改欧拉函数筛法bug

Author: taotao

Diff for: math/莫比乌斯反演笔记.md

@@ -60,9 +60,9 @@ void phi_table(){
         }
         for(int j=0 ; j<cnt && i*prime[j]<maxn ; ++j){
             prime[i*prime[j]] = 1;
-            if(i%prime[j])phi[prime[j]*i] = phi[i]*(phi[prime[j]]-1);
+            if(i%prime[j])phi[prime[j]*i] = phi[i]*(phi[prime[j]]);
             else {
-                phi[i*prime[j]]= phi[i]*phi[prime[j]];
+                phi[i*prime[j]]= phi[i]*prime[j];
                 break;
             }
         }