12.22+22.32+32.42……….up to n’th term.

#include<stdio.h>
#include<conio.h>
#include<iostream.h>

void main()
{
    int n;
    clrscr();
    cout<<"Enter how many number you sum = ";
    cin>>n;
    long int s=0;
    for(int i=1;i<=n;i++)
    s=s+i*i*(i+1)*(i+1);

    cout<<"Summation = "<<s;

    getch();
}

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Copy & paste this code in your TC & run, then you will get output.......
If you have any problem please comment below.........