This is the 4716th most frequent Polish word.
niejeden
"More than one; quite a few; some."
In this sentence, 'niejeden' functions as an indefinite pronoun to specify multiple instances of an event or action.
Niejeden raz myślałem o podróży do Japonii.
More than once, I thought about traveling to Japan.
Here, 'niejeden' emphasizes the multiplicity of subjects involved in the statement—more than one student is implied.
Niejeden uczeń ma trudności z matematyką.
More than one student has difficulties with mathematics.
In this context, 'niejeden' is used to denote a number of individuals sharing a similar sentiment, i.e., delight in the performance.