Determine the sum of the series S=∑n=1∞n2n!S = \sum_{n=1}^{\infty} \frac{n^2}{n!}S=∑n=1∞n!n2.
S=eS = eS=e
S=2eS = 2eS=2e
S=e2S = e^2S=e2
S=0S = 0S=0