C :

#include<stdio.h>
int main()
{
	int n,i,j;
	scanf("%d",&n);
	int a[n][n];
	for(i=0;i<n;i++){
		a[i][0]=i+1;
		for(j=1;j<=i;j++){
			a[i][j]=a[i][j-1];
		}
		for(j=i+1;j<n;j++){
			a[i][j]=a[i][j-1]+1;
		}
	}
	for(i=0;i<n;i++){
		for(j=0;j<n;j++){
			printf("%3d",a[i][j]);
		}
		printf("\n");
	}
return 0;
}

C++ :

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

int main(){
	int a[10][10] = {0};
	int i,j,n;
	cin>>n;
	
	for (i = 0;i < n;i++){
		for (j = 0;j <= i;j++){
			a[i][j] = i + 1;
			a[j][i] = i + 1;
		}
	}
	
	for (i = 0;i < n;i++){
		for (j = 0;j < n;j++){
			cout<<setw(3)<<a[i][j];
		}
		cout<<endl;
	}
}

Python :

n = int(input())
a = [[0 for j in range(n)] for i in range(n)]

for i in range(n):
    # 先定好第一列数字
    a[i][0] = i+1
    for j in range(1, i + 1):
        a[i][j] = a[i][0]
    for j in range(i + 1, n):
        a[i][j] = a[i][j - 1] + 1

for i in range(n):
    for j in range(n):
        print('%3d' % a[i][j], end='')
    print()