Stirling Number of the Second Kind of n+1 with 0

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Theorem

Let $n \in \Z_{\ge 0}$.

Then:

$\ds {n + 1 \brace 0} = 0$

where $\ds {n + 1 \brace 0}$ denotes a Stirling number of the second kind.


Proof

We are given that $k = 0$.

So by definition of unsigned Stirling number of the first kind:

$\ds {n \brace k} = \delta_{n k}$

where $\delta_{n k}$ is the Kronecker delta.

Thus

\(\ds n\) \(\ge\) \(\ds 0\) by hypothesis
\(\ds \leadsto \ \ \) \(\ds n + 1\) \(>\) \(\ds 0\)
\(\ds \leadsto \ \ \) \(\ds n + 1\) \(\ne\) \(\ds 0\)
\(\ds \leadsto \ \ \) \(\ds \delta_{\paren {n + 1} 0}\) \(=\) \(\ds 0\)


Hence the result.

$\blacksquare$


Also see


Sources