Partial sums & series

The $n\text{th}$n, start text, t, h, end text partial sum of the series $S$S is given by

$\displaystyle{{S}_{n}}=2-\frac{4n}{{{n}^{3}+6}}$S, start subscript, n, end subscript, equals, 2, minus, start fraction, 4, n, divided by, n, cubed, plus, 6, end fraction.

$S=$S, equals