Generate an incrementally increasing sequence like 112123123412345

Question

Basically I want to generate a sequence, say:

n is 2, the sequence will be 112
n is 3, sequence is 112123
n is 5, sequence is 112123123412345

I did

Answer 1

Use sequence:

> sequence(1:5)
 [1] 1 1 2 1 2 3 1 2 3 4 1 2 3 4 5