A sequence of numbers SnS_nSn is defined as Sn=Sn−1+(2n)S_n = S_{n-1} + (2n)Sn=Sn−1+(2n) for n≥1n \ge 1n≥1, with S0=1S_0 = 1S0=1. What is the value of S2S_2S2?
111
333
777
999