7, 9, 16, 25, 41, ?, 107, 173

As per the details in the question the series is in the form of
First term + Second term = Third term
? 7 + 9 = 16;
Second term + Third term = Fourth term
? 9 + 16 = 25;
Similarly , we can find all others terms also.
Third term + Fourth term = Fifth term
? 16 + 25 = 41;
Fourth term + Fifth term = Sixth term
? 25 + 41 = ?
? ? = 66
Fifth term + Sixth term = Seventh term
? 41 + 66 = 107
Sixth term + Seventh term = Eighth term
? 66 + 107 = 173
Hence , Sixth term = 66