Taking common difference d=6 (from first three terms 7, 13, 19): an=7+(n−1)×6=97 gives (n−1)=15, so n=16.
Note: The printed sequence 7, 13, 19, 26 has an irregular step (26 instead of 25). We treat it as an AP with d=6, which makes 97 the 16th term.