 | ECS #386 |
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1. Description
No description available
2. Specification
This unlabelled structure is specified as S in
\displaystyle
\left\{ S={\rm Union} \left( {\rm Sequence} \left( Z \right) ,{\rm
Prod} \left( Z,{\rm Sequence} \left( Z \right) ,{\rm Sequence} \left( Z
\right) ,{\rm Sequence} \left( Z \right) \right) \right) \right\}
other formats
3. Coefficients
3.1. First terms
3.2. Recurrence
\displaystyle
\left\{ -2\,f \left( n \right) +{n}^{2}+n+2=0,f \left( 0 \right) =1,f
\left( 1 \right) =2,f \left( 2 \right) =4 \right\}
other formats
3.3. Closed form
\displaystyle
1/2\,{n}^{2}+1/2\,n+1
other formats
3.4. Asymptotics
4. Ordinary generating function
\displaystyle
-{\frac {1-x+{x}^{2}}{ \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).