#include <stdio.h>

void inv_tri(int);

int main (void)
{
    inv_tri(4);

    return 0;
}

void inv_tri(int num)
{
    for (int i = num * num; i > (num - 1) * (num - 1); i--)
        printf("%2d ", i);

    printf("\n%*.s", 3 * (5 - num), "");

    if (num > 0)
        inv_tri(num - 1);
}