how to create user defined functions in R

In this video i have covered the how to create user defined funtions in R

[LaaHiruFernando]

Write down a function to get the following output. Your function should have only one argument, n.

Please note that, n = 5 is for the following output.

1 2

1 2 3

1 2 3 4

1 2 3 4 5
how can i do this?