Recurring events for yearly with interval.

I want to show recurring appointment yearly for following condition

  1. 2nd year on 3rd Thursday of may.
  2. yearly on may 15 interval is 1.

What is the condition for that?

Thanks in advance.

start_date: may 1
rec_type: year_2_4_3_

start_date: may 15
rec_type: year_1___