Av(1342, 13254)
Counting Sequence
      
        1, 1, 2, 6, 23, 102, 495, 2549, 13682, 75714, 428882, 2474573, 14492346, 85926361, 514763279, ...
      
      
    
        Implicit Equation for the Generating Function
        
      
      
      
        \(\displaystyle \left(x^{2}-x +1\right) F \left(x
      \right)^{3}+\left(x -3\right) F \left(x
      \right)^{2}+3 F \! \left(x \right)-1 = 0\)
      
      
      
    Recurrence
      
        
        
        \(\displaystyle a \! \left(0\right) = 1\)
\(\displaystyle a \! \left(1\right) = 1\)
\(\displaystyle a \! \left(2\right) = 2\)
\(\displaystyle a \! \left(3\right) = 6\)
\(\displaystyle a \! \left(n +4\right) = \frac{24 \left(3 n +4\right) \left(3 n +2\right) a \! \left(n \right)}{\left(2 n +7\right) \left(n +3\right)}-\frac{\left(469 n^{2}+953 n +378\right) a \! \left(n +1\right)}{2 \left(2 n +7\right) \left(n +3\right)}+\frac{3 \left(155 n^{2}+309 n +112\right) a \! \left(n +2\right)}{2 \left(2 n +7\right) \left(n +3\right)}-\frac{3 \left(11 n^{2}+21 n -16\right) a \! \left(n +3\right)}{2 \left(2 n +7\right) \left(n +3\right)}, \quad n \geq 4\)
      
    \(\displaystyle a \! \left(1\right) = 1\)
\(\displaystyle a \! \left(2\right) = 2\)
\(\displaystyle a \! \left(3\right) = 6\)
\(\displaystyle a \! \left(n +4\right) = \frac{24 \left(3 n +4\right) \left(3 n +2\right) a \! \left(n \right)}{\left(2 n +7\right) \left(n +3\right)}-\frac{\left(469 n^{2}+953 n +378\right) a \! \left(n +1\right)}{2 \left(2 n +7\right) \left(n +3\right)}+\frac{3 \left(155 n^{2}+309 n +112\right) a \! \left(n +2\right)}{2 \left(2 n +7\right) \left(n +3\right)}-\frac{3 \left(11 n^{2}+21 n -16\right) a \! \left(n +3\right)}{2 \left(2 n +7\right) \left(n +3\right)}, \quad n \geq 4\)
This specification was found using the strategy pack "Point And Row Placements Tracked Fusion Req Corrob Expand Verified" and has 22 rules.
Found on January 22, 2022.Finding the specification took 62 seconds.
            
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              \(\begin{align*}
                
                F_{0}\! \left(x \right) &= F_{1}\! \left(x \right)+F_{2}\! \left(x \right)\\
                
                F_{1}\! \left(x \right) &= 1\\
                
                F_{2}\! \left(x \right) &= F_{3}\! \left(x \right)\\
                
                F_{3}\! \left(x \right) &= F_{19}\! \left(x \right) F_{4}\! \left(x \right)\\
                
                F_{4}\! \left(x \right) &= F_{0}\! \left(x \right)+F_{5}\! \left(x \right)\\
                
                F_{5}\! \left(x \right) &= F_{6}\! \left(x \right)\\
                
                F_{6}\! \left(x \right) &= F_{0}\! \left(x \right) F_{19}\! \left(x \right) F_{7}\! \left(x \right)\\
                
                F_{7}\! \left(x \right) &= F_{8}\! \left(x , 1\right)\\
                
                F_{8}\! \left(x , y\right) &= F_{1}\! \left(x \right)+F_{15}\! \left(x , y\right)+F_{20}\! \left(x , y\right)+F_{9}\! \left(x , y\right)\\
                
                F_{9}\! \left(x , y\right) &= F_{10}\! \left(x , y\right)\\
                
                F_{10}\! \left(x , y\right) &= F_{11}\! \left(x , y\right) F_{14}\! \left(x , y\right) F_{8}\! \left(x , y\right)\\
                
                F_{11}\! \left(x , y\right) &= F_{1}\! \left(x \right)+F_{12}\! \left(x , y\right)\\
                
                F_{12}\! \left(x , y\right) &= F_{13}\! \left(x , y\right)\\
                
                F_{13}\! \left(x , y\right) &= F_{11}\! \left(x , y\right)^{2} F_{14}\! \left(x , y\right)\\
                
                F_{14}\! \left(x , y\right) &= y x\\
                
                F_{15}\! \left(x , y\right) &= F_{16}\! \left(x , y\right) F_{19}\! \left(x \right)\\
                
                F_{16}\! \left(x , y\right) &= F_{17}\! \left(x , y\right)+F_{8}\! \left(x , y\right)\\
                
                F_{17}\! \left(x , y\right) &= F_{18}\! \left(x , y\right)\\
                
                F_{18}\! \left(x , y\right) &= F_{19}\! \left(x \right) F_{7}\! \left(x \right) F_{8}\! \left(x , y\right)\\
                
                F_{19}\! \left(x \right) &= x\\
                
                F_{20}\! \left(x , y\right) &= F_{19}\! \left(x \right) F_{21}\! \left(x , y\right)\\
                
                F_{21}\! \left(x , y\right) &= -\frac{-y F_{8}\! \left(x , y\right)+F_{8}\! \left(x , 1\right)}{-1+y}\\
                
                \end{align*}\)
            
          This specification was found using the strategy pack "Point Placements Tracked Fusion Expand Verified" and has 24 rules.
Found on January 22, 2022.Finding the specification took 120 seconds.
            
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              \(\begin{align*}
                
                F_{0}\! \left(x \right) &= F_{1}\! \left(x \right)+F_{2}\! \left(x \right)\\
                
                F_{1}\! \left(x \right) &= 1\\
                
                F_{2}\! \left(x \right) &= F_{3}\! \left(x \right)\\
                
                F_{3}\! \left(x \right) &= F_{16}\! \left(x \right) F_{4}\! \left(x \right)\\
                
                F_{4}\! \left(x \right) &= F_{0}\! \left(x \right)+F_{5}\! \left(x \right)\\
                
                F_{5}\! \left(x \right) &= F_{6}\! \left(x \right)\\
                
                F_{6}\! \left(x \right) &= F_{0}\! \left(x \right) F_{16}\! \left(x \right) F_{7}\! \left(x \right)\\
                
                F_{7}\! \left(x \right) &= F_{8}\! \left(x , 1\right)\\
                
                F_{8}\! \left(x , y\right) &= F_{17}\! \left(x , y\right)+F_{9}\! \left(x , y\right)\\
                
                F_{9}\! \left(x , y\right) &= F_{10}\! \left(x , y\right)+F_{14}\! \left(x , y\right)\\
                
                F_{10}\! \left(x , y\right) &= F_{1}\! \left(x \right)+F_{11}\! \left(x , y\right)\\
                
                F_{11}\! \left(x , y\right) &= F_{12}\! \left(x , y\right)\\
                
                F_{12}\! \left(x , y\right) &= F_{10}\! \left(x , y\right)^{2} F_{13}\! \left(x , y\right)\\
                
                F_{13}\! \left(x , y\right) &= y x\\
                
                F_{14}\! \left(x , y\right) &= F_{15}\! \left(x , y\right)\\
                
                F_{15}\! \left(x , y\right) &= F_{10}\! \left(x , y\right) F_{16}\! \left(x \right) F_{8}\! \left(x , y\right)\\
                
                F_{16}\! \left(x \right) &= x\\
                
                F_{17}\! \left(x , y\right) &= F_{18}\! \left(x , y\right)\\
                
                F_{18}\! \left(x , y\right) &= F_{16}\! \left(x \right) F_{19}\! \left(x , y\right)\\
                
                F_{19}\! \left(x , y\right) &= F_{20}\! \left(x , y\right)+F_{21}\! \left(x , y\right)\\
                
                F_{20}\! \left(x , y\right) &= F_{7}\! \left(x \right) F_{9}\! \left(x , y\right)\\
                
                F_{21}\! \left(x , y\right) &= F_{10}\! \left(x , y\right) F_{22}\! \left(x , y\right)\\
                
                F_{22}\! \left(x , y\right) &= -\frac{y \left(F_{23}\! \left(x , 1\right)-F_{23}\! \left(x , y\right)\right)}{-1+y}\\
                
                F_{8}\! \left(x , y\right) &= F_{23}\! \left(x , y\right)+F_{4}\! \left(x \right)\\
                
                \end{align*}\)