Sorry. That's not enough information to pin-point just one solution.

__, 3,__,__,__,__,__,__,__,__,__,__,__,__,__,__,__

There are trillions of ways to fill those blanks. 

One way is

 1, 3, 5, 7, 9,11,13,15,17,19,21,23,25,27,29,31,33

Another way is

 0, 3, 6, 9,12,15,18,21,24,27,30,33,36,39,42,45,48

Another way is

 2, 3, 4, 5, 6, 7, 8, 9,10,11,12,13,14,15,16,17,18

Another way is:

-3, 3,-3, 3,-3, 3,-3, 3,-3, 3,-3, 3,-3, 3,-3, 3,-3

Another way is

 4, 3, 0,-1,-2,-3,-4,-5,-6,-7,-8,-9,-10,-11,-12,-13,-14

etc., etc., etc.

All those have 3 as the 2nd term, and all have 17 terms.

You have left out something that is necessary for the problem just 
to have one solution.  Tell us what it is in the thank-you note form
below and we'll get back to you.  But you must be given a sum of
terms, or another term, or something.  Also you must be given whether 
it is an arithmetic or a geometric sequence.  

Edwin