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
- Unsigned Stirling Number of the First Kind of n+1 with 0
- Signed Stirling Number of the First Kind of n+1 with 0
Sources
- 1997: Donald E. Knuth: The Art of Computer Programming: Volume 1: Fundamental Algorithms (3rd ed.) ... (previous) ... (next): $\S 1.2.6$: Binomial Coefficients: $(50)$