1
Input:
Integer n which is >=0 or >=1 (f(0) is optional)
Output:
The n'th number in the sequence below, OR the sequence up to and including the n'th number.
Sequence:
(0),1,-1,-3,0,5,-1,-7,0,9,-1,-11,0,13,-1,-15,0,17,-1,-19,0,21,-1,-23,0,25,-1,-27,0,29,-1,-31,0,33,-1,-35,0,37,-1,-39,0,41,-1,-...