Proposition: Comparison between the Stirling numbers of the First and Second Kind

The Stirling numbers of the first and the second kind obey the following inequality:

$$\left[\begin{array}{c}n\\r\end{array}\right]\ge \left\{\begin{array}{c}n\\r\end{array}\right\},\quad n,r\ge 0.$$ Equality holds for $r=n$ and for $r=n-1,$ in particular $$\left[\begin{array}{c}n\\n\end{array}\right]=\left\{\begin{array}{c}n\\n\end{array}\right\}=1,\quad \left[\begin{array}{c}n\\n-1\end{array}\right]=\left\{\begin{array}{c}n\\n-1\end{array}\right\}=\binom n{2}=\frac{n(n-1)}{2}.$$

Proofs: 1


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References

Bibliography

  1. Graham L. Ronald, Knuth E. Donald, Patashnik Oren: "Concrete Mathematics", Addison-Wesley, 1994, 2nd Edition