Series a01/a02

#include <iostream>
using namespace std;
class Series {
private:
    int n,i,sum=0,a=2,b=0;
public:

void input () {
cout<<"Enter series Length : ";
cin>>n;

}
void Series1 () {
    cout<<endl;
      cout<<"Series 1 : "<<endl;
    cout<<"1+ 2 + ";

for(i=2;i<=n;i++) {

   b=a+i;
   a=b;
sum=sum+b;
 cout<<b<<" + ";
    //sum=sum+i;


    }
   cout<<"\b\b = "<<sum+1+2<<endl;
 }
 void series2(){
     cout<<endl;
     cout<<"Series 2 : "<<endl;
 for (int i=1; i<n;i++)
 {
     if(i%2!=0)
     {
         cout<<i<<" ";
     }
     else
        cout<<i*2<<" ";
 }

 }

};
int main()
{

    Series obj;
    obj.input();
    obj.Series1();
    obj.series2();
    return 0;
}