"find the sum of the series 2^2+4^2+6^2+...+n^2 using for loop" in c .

  //find the sum of the series 2^2+4^2+6^2+...+n^2 using for loop

 //where  n is the positive even integer

 #include <stdio.h >

 int main ()

 {

    int n,i,sum ;

    printf ("enter any positive even integer  i.e n :");

    scanf ("%i",&n);

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

    sum=sum + i*i;

}

printf ("the  sum of the series is :%i",sum);

return 0;

 }