 | ECS #262: Arrangements |
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1. Description
Arrangements of n labelled objects in 3 rows
2. Specification
This unlabelled structure is specified as S in
\displaystyle
\left\{ B={\rm Sequence} \left( Z \right) ,S={\rm Prod} \left( B,B,B
\right) \right\}
other formats
3. Coefficients
3.1. First terms
3.2. Recurrence
\displaystyle
\left\{ -2\,f \left( n \right) +{n}^{2}+3\,n+2=0,f \left( 0 \right) =1
\right\}
other formats
3.3. Closed form
\displaystyle
1/2\, \left( n+1 \right) \left( n+2 \right)
other formats
3.4. Asymptotics
4. Ordinary generating function
\displaystyle
- \left( -1+x \right) ^{-3}
other formats
5. References
6. Random structure
Search a combinatorial structure by: (firstTerms should be a sequence of integers, separated by commas).