Which recursive formula describes the sum Sn=1+2+3+⋯+nS_n = 1 + 2 + 3 + \dots + nSn=1+2+3+⋯+n?
Sn=Sn−1+nS_n = S_{n-1} + nSn=Sn−1+n
Sn=Sn−1⋅nS_n = S_{n-1} \cdot nSn=Sn−1⋅n
Sn=n⋅Sn−1S_n = n \cdot S_{n-1}Sn=n⋅Sn−1
Sn=Sn−1+1S_n = S_{n-1} + 1Sn=Sn−1+1