Find the missing term: 2, 9, 28, ?, 126, 126, 217, 344

Explanation:-

The given series is a triangular pattern series.
So, we have
Series I :  2     9     28     ?
                126   217    344
Series II :  7     19     ?
                ?   91    127
Series III :       12     ?     ?
                ?   36
Clearly, to form a pattern, the missing terms in Series III must be 18, 24, 30
So, missing term
= 127 + (61 + 24 + 6)
= 127 + 91
= 218