C++ :

#include<bits/stdc++.h>
using namespace std;
int main()
{
    int n,k=1;
    cin>>n;
    int a[n+2][n+2];
    int x=1,y=1,fx=1;
    for(int i=1;i<=n;i++)
        for(int j=1;j<=n;j++)
            a[i][j]=0;
    for(int i=1;i<=n*n;i++)
    {
        a[x][y]=i;
//      cout<<x<<" "<<y<<endl;
        if(x==1)
        {
        	k++;
        	x=k;y=1;
		}
		else
		{
			x--;y++;
		}
    }
    for(int i=1;i<=n;i++)
    {
        for(int j=1;j<=n-i+1;j++)
            printf("%4d",a[i][j]);
        cout<<endl;
    }
    return 0;
}

Pascal :

var
  a:array[1..1000,1..1000] of longint;
  i,j,n:longint;
begin
  readln(n);
  a[1,1]:=1;
  for i:=2 to n do
    a[i,1]:=a[i-1,1]+i-1;
  for i:=2 to n do
    a[1,i]:=a[1,i-1]+i;
  for i:=2 to n do
    for j:=2 to n-i+1 do
      a[i,j]:=a[i-1,j+1]-1;
  for i:=1 to n do
    begin
      for j:=1 to n do
        if a[i,j]<>0 then
          write(a[i,j]:4);
       writeln;
    end;
end.