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The value of $\sum_{r = 1}^{n} \frac{{n_{P}}_{r}}{r!}$ , is

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Correct option is B

We have nPr=nCrr!⇒ nPrr!=nCr⇒∑r=1n nPrr!=∑r−1n nCr=nC1+nC2+…+nCn=2n−1

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The value of ∑r=1n nPrr!, is

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The value of $\sum_{r = 1}^{n} \frac{{n_{P}}_{r}}{r!}$ , is