3. Use matrix( ), rep( ), and seq( ) to construct the following 5 × 5 matrix:
[ , 1] [ , 2] [ , 3] [ , 4] [ , 5]
[1, ] 1 2 3 4 5
[2, ] 2 3 4 5 6
[3, ] 3 4 5 6 7
[4, ] 4 5 6 7 8
[5, ] 5 6 7 8 9 另外构建一个函数可以生成这种模式的矩阵
use your code to specify a function that can be used to construct n × n matrices that have the
same pattern. Use the function to generate 10 × 10 and 12 × 12 matrices
本人菜鸟一个，刚学。