INTRODUCING 5 - days-a-week problem solving session for Math Olympiad and ISI Entrance. Learn More 

March 15, 2021

What is Stirling Number of First Kind

We will learn about a combinatorics tool: Stirling Numbers of First Kind. Here is a video to get you started.

Problem 1

Show that
s(r, n)=s(r-1, n-1)+(r-1) s(r-1, n)
where $r, n \in \mathbf{N}$ with $n \leq r$

Problem 2

Show the following:

$$ s(r, 0)=0 \text { if } r \geq 1 $$

$$ s(r, r)=1 \text { if } r \geq 0 $$

$$ s(r, 1)=(r-1)! \text { for } r \geq 2 $$

$$ s(r, r-1)={{r} \choose {2}} $$

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Cheenta. Passion for Mathematics

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