‘One of the assistant’ needs to be replaced with ‘one of the assistants’ to make the sentence grammatically and contextually correct. This is because, ‘One of’ is always followed by a plural noun.
Clearly, the numerators of the fractions in the given sequence follow the series of 2, 3, 5, 7,... and the denominator follows 3, 9, 27, 81, 243, ... Then, the next term in the given sequence is .