Math 2.0

Number theory Theorem

Recurrence for Bell numbers

Builds on Binomial coefficientBell numbers

Statement

Let nn be a natural number, and let BmB_m be the Bell numbers. Then Bn+1=∑k=0n(nk)Bk.B_{n+1} = \sum_{k=0}^{n} \binom{n}{k} B_k.

Remarks

Proof idea: in a partition of {1,…,n+1}\{1, \dots, n + 1\}, the block of n+1n + 1 contains n−kn - k other elements, for some kk. The remaining kk elements form an arbitrary partition. Example: B4=1⋅1+3⋅1+3⋅2+1⋅5=15B_4 = 1 \cdot 1 + 3 \cdot 1 + 3 \cdot 2 + 1 \cdot 5 = 15.

Reading path

To understand this page from the ground up, read these 4 pages in order. The foundations come first.

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Each page uses the pages above it. The colour of the bar on a box shows how strong the evidence is, and the box also gives it as text. The list has the same pages.
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  1. Binomial coefficient definition
  2. Stirling numbers of the second kind definition
  3. Bell numbers definition
  4. Recurrence for Bell numbers statement

Further reading

  1. Web https://en.wikipedia.org/wiki/Bell_number, Summation formulas
About this page
Tag0110GBHPPB
URIm2://0110GBHPPB
Kindstatement, theorem
WritingW0 stub
MSC11B73
StatusThis copy of the site has no build data. Run m2 status 0110GBHPPB.
UsesBinomial coefficient, Bell numbers

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