C++ :

#include<iostream>
#include<iomanip>
using namespace std;

int main()
{
	int n;
	cin>>n;int a[21][21];
	for (int i=1,k=0; i<=n; i++)
		for (int j=1,x=i; x>=1; j++) a[x--][j]=k++;
	for (int i=1; i<=n; i++)
	{
		for (int j=1; j<=n-i+1; j++) cout<<setw(4)<<a[i][j];
		cout<<endl;
	}
	return 0;
}