In this HackerEarth Digit cube problem solution, A robot's initial position is (0,0) and it can only move along X-axis. It has N moves to make and in each move, it will select one of the following options:
  1. Go to (X - 1,0) from (X,0)
  2. Go to (X + 1,0) from (X,0)
  3. Remain at its current position
Your task is to calculate sigma(abs(X) + abs(Y)) for all reachable (X,Y).

hackerEarth Robotic moves problem solution

HackerEarth Robotic moves problem solution.

using namespace std;
#define FIO ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0)
#define mod 1000000007
#define endl "\n"
#define test ll txtc; cin>>txtc; while(txtc--)
typedef long long int ll;
typedef long double ld;
int main() {
      ll n; cin>>n;
      ll ans=n*(n+1);
	return 0;

second solution

t = int(input())
while t > 0:
    t -= 1
    n = int(input())
    print(n * (n + 1))