GETTING AN AP

problem statement is here

#include<stdio.h>

long long gcd(long long m,long long n){

 if(n==0)

  return m;

 else 

  return gcd(n,m%n);

}

long long calcu(long long a,long long n){

long long u,c,d;

u=0;

if(n%2==0){

c=(a-n)/2;

c--;

d=(a-1)/2;

u=(d*(d+1))/2;

u=u-(c*(c+1))/2;

u*=2;

}else{

c=(a-n)/2;

c--;

d=(a-2)/2;

u=(d*(d+1))/2;

u=u-(c*(c+1))/2;

u*=2;

u+=((a-1)/2);

}

u+=n;

return u;

}

int main(){

long long a,b,n,p,t;

scanf("%lld",&t);

while(t--){

scanf("%lld",&n);

a=calcu(3*n,n)+calcu(n,n-2);

a-=(n-2);

p=n*2*n*3*n;

b=gcd(a,p);

a/=b;

p/=b;

printf("%lld/%lld\n",a,p);

}

return 0;

}