Find the sixth term in the series - 1, 6, 21, 60, ?

Question

Find the next term in the series- 0, 1, 1, 1, 2, 2, 3, ?

One of the following is correct answer, which?
1) 3
2) 4
3) 5
4) 6

Answer 1

Looks like it is as continuation of even terms 6->60->600