 | ECS #471: A simple regular expression |
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1. Description
No description available
2. Specification
This unlabelled structure is specified as S in
\displaystyle
\left\{ S={\rm Prod} \left( {\rm Union} \left( Z,{\rm Sequence}
\left( Z \right) \right) ,{\rm Sequence} \left( Z \right) ,{\rm
Sequence} \left( Z \right) \right) \right\}
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3. Coefficients
3.1. First terms
3.2. Recurrence
\displaystyle
\left\{ -2\,f \left( n \right) +{n}^{2}+5\,n+2=0,f \left( 0 \right) =1
,f \left( 1 \right) =4,f \left( 2 \right) =8 \right\}
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3.3. Closed form
\displaystyle
1/2\,{n}^{2}+5/2\,n+1
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3.4. Asymptotics
4. Ordinary generating function
\displaystyle
{\frac {-x+{x}^{2}-1}{ \left( -1+x \right) ^{3}}}
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5. References
6. Random structure
Search a combinatorial structure by: (firstTerms should be a sequence of integers, separated by commas).