 | ECS #596: A simple regular expression in a labelled universe |
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1. Description
No description available
2. Specification
This labelled structure is specified as S in
\displaystyle
\left\{ S={\rm Prod} \left( {\rm Sequence} \left( Z \right) ,{\rm
Union} \left( Z,{\rm Sequence} \left( Z \right) ,{\rm Sequence} \left(
Z \right) \right) \right) \right\}
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3. Coefficients
3.1. First terms
3.2. Recurrence
\displaystyle
\left\{ \left( -2\,{n}^{2}-7\,n-5 \right) f \left( n \right) +
\left( 2\,n+3 \right) f \left( n+1 \right) =0,f \left( 0 \right) =2,f
\left( 1 \right) =5,f \left( 2 \right) =14,f \left( 3 \right) =54
\right\}
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3.3. Closed form
\displaystyle
\left( 2\,n+3+\cases{-1&$n=0$\cr 0&otherwise\cr} \right) n!
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3.4. Asymptotics
4. Exponential generating function
\displaystyle
-{\frac {-x+{x}^{2}-2}{ \left( -1+x \right) ^{2}}}
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5. References
6. Random structure
Search a combinatorial structure by: (firstTerms should be a sequence of integers, separated by commas).