Finding the nth term of a series

问题

Find the n'th term of DJ(i).

Given DJ(i) is the number of times i is present in DJ(i)

The array DJ(i) is as shown:

   i       1 2 3 4 5 6 7 8 9 10 ..... 
DJ(i)      1 2 2 3 3 4 4 4 5  5 .....

I want the nth term of the series DJ(i). I have to carry out some further calculations with the term.

回答1:

Look up the value in this table or compute yourself the table in the programming language of your choice (left as an easy exercise). Also check this SO answer and OEIS.

来源：https://stackoverflow.com/questions/12881980/finding-the-nth-term-of-a-series