Av(1234, 1324, 1342, 2341, 4123)
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Generating Function
\(\displaystyle \frac{-2 \left(-1+x \right)^{5} \left(x -\frac{1}{2}\right) \sqrt{1-4 x}-2 x^{7}+4 x^{6}-15 x^{5}+27 x^{4}-30 x^{3}+20 x^{2}-7 x +1}{2 x \left(2 x -1\right) \left(-1+x \right)^{5}}\)
Counting Sequence
1, 1, 2, 6, 19, 58, 173, 521, 1620, 5235, 17508, 60129, 210543, 747698, 2683619, ...
Implicit Equation for the Generating Function
\(\displaystyle x \left(2 x -1\right)^{2} \left(-1+x \right)^{10} F \left(x \right)^{2}+\left(2 x -1\right) \left(2 x^{7}-4 x^{6}+15 x^{5}-27 x^{4}+30 x^{3}-20 x^{2}+7 x -1\right) \left(-1+x \right)^{5} F \! \left(x \right)+x^{13}-26 x^{11}+175 x^{10}-585 x^{9}+1250 x^{8}-1855 x^{7}+1980 x^{6}-1537 x^{5}+861 x^{4}-339 x^{3}+89 x^{2}-14 x +1 = 0\)
Recurrence
\(\displaystyle a \! \left(0\right) = 1\)
\(\displaystyle a \! \left(1\right) = 1\)
\(\displaystyle a \! \left(2\right) = 2\)
\(\displaystyle a \! \left(3\right) = 6\)
\(\displaystyle a \! \left(4\right) = 19\)
\(\displaystyle a \! \left(5\right) = 58\)
\(\displaystyle a \! \left(6\right) = 173\)
\(\displaystyle a \! \left(7\right) = 521\)
\(\displaystyle a \! \left(8\right) = 1620\)
\(\displaystyle a \! \left(9\right) = 5235\)
\(\displaystyle a \! \left(n +3\right) = \frac{8 \left(2 n +1\right) a \! \left(n \right)}{n +4}-\frac{4 \left(5 n +8\right) a \! \left(n +1\right)}{n +4}+\frac{2 \left(4 n +11\right) a \! \left(n +2\right)}{n +4}-\frac{n \left(3 n^{4}-52 n^{3}+213 n^{2}-176 n +132\right)}{24 \left(n +4\right)}, \quad n \geq 10\)

This specification was found using the strategy pack "Requirement Placements Tracked Fusion" and has 88 rules.

Found on July 23, 2021.

Finding the specification took 11 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_{4}\! \left(x \right) F_{9}\! \left(x \right)\\ F_{4}\! \left(x \right) &= F_{5}\! \left(x \right)+F_{63}\! \left(x \right)\\ F_{5}\! \left(x \right) &= F_{10}\! \left(x \right)+F_{6}\! \left(x \right)\\ F_{6}\! \left(x \right) &= F_{1}\! \left(x \right)+F_{7}\! \left(x \right)\\ F_{7}\! \left(x \right) &= F_{8}\! \left(x \right)\\ F_{8}\! \left(x \right) &= F_{6}\! \left(x \right) F_{9}\! \left(x \right)\\ F_{9}\! \left(x \right) &= x\\ F_{10}\! \left(x \right) &= F_{11}\! \left(x \right)+F_{23}\! \left(x \right)\\ F_{11}\! \left(x \right) &= F_{12}\! \left(x \right)\\ F_{12}\! \left(x \right) &= F_{13}\! \left(x \right) F_{9}\! \left(x \right)\\ F_{13}\! \left(x \right) &= F_{14}\! \left(x \right)+F_{15}\! \left(x \right)\\ F_{14}\! \left(x \right) &= F_{1}\! \left(x \right)+F_{9}\! \left(x \right)\\ F_{15}\! \left(x \right) &= F_{11}\! \left(x \right)+F_{16}\! \left(x \right)\\ F_{16}\! \left(x \right) &= F_{17}\! \left(x \right)+F_{18}\! \left(x \right)+F_{22}\! \left(x \right)\\ F_{17}\! \left(x \right) &= 0\\ F_{18}\! \left(x \right) &= F_{19}\! \left(x \right) F_{9}\! \left(x \right)\\ F_{19}\! \left(x \right) &= F_{20}\! \left(x \right)+F_{21}\! \left(x \right)\\ F_{20}\! \left(x \right) &= F_{9}\! \left(x \right)\\ F_{21}\! \left(x \right) &= F_{16}\! \left(x \right)\\ F_{22}\! \left(x \right) &= F_{11}\! \left(x \right) F_{9}\! \left(x \right)\\ F_{23}\! \left(x \right) &= F_{17}\! \left(x \right)+F_{24}\! \left(x \right)+F_{58}\! \left(x \right)\\ F_{24}\! \left(x \right) &= F_{25}\! \left(x \right) F_{9}\! \left(x \right)\\ F_{25}\! \left(x \right) &= F_{26}\! \left(x \right)+F_{31}\! \left(x \right)\\ F_{26}\! \left(x \right) &= F_{27}\! \left(x \right)+F_{7}\! \left(x \right)\\ F_{27}\! \left(x \right) &= F_{17}\! \left(x \right)+F_{28}\! \left(x \right)+F_{29}\! \left(x \right)\\ F_{28}\! \left(x \right) &= F_{7}\! \left(x \right) F_{9}\! \left(x \right)\\ F_{29}\! \left(x \right) &= F_{30}\! \left(x \right) F_{9}\! \left(x \right)\\ F_{30}\! \left(x \right) &= F_{27}\! \left(x \right)+F_{9}\! \left(x \right)\\ F_{31}\! \left(x \right) &= F_{23}\! \left(x \right)+F_{32}\! \left(x \right)\\ F_{32}\! \left(x \right) &= F_{17}\! \left(x \right)+F_{33}\! \left(x \right)+F_{37}\! \left(x \right)+F_{49}\! \left(x \right)\\ F_{33}\! \left(x \right) &= F_{34}\! \left(x \right) F_{9}\! \left(x \right)\\ F_{34}\! \left(x \right) &= F_{35}\! \left(x \right)+F_{36}\! \left(x \right)\\ F_{35}\! \left(x \right) &= F_{27}\! \left(x \right)\\ F_{36}\! \left(x \right) &= F_{32}\! \left(x \right)\\ F_{37}\! \left(x \right) &= F_{38}\! \left(x \right) F_{9}\! \left(x \right)\\ F_{38}\! \left(x \right) &= F_{39}\! \left(x \right)\\ F_{39}\! \left(x \right) &= F_{40}\! \left(x \right) F_{9}\! \left(x \right)\\ F_{40}\! \left(x \right) &= F_{41}\! \left(x \right)+F_{43}\! \left(x \right)\\ F_{41}\! \left(x \right) &= F_{42}\! \left(x \right)+F_{7}\! \left(x \right)\\ F_{42}\! \left(x \right) &= F_{28}\! \left(x \right)\\ F_{43}\! \left(x \right) &= F_{38}\! \left(x \right)+F_{44}\! \left(x \right)\\ F_{44}\! \left(x \right) &= 2 F_{17}\! \left(x \right)+F_{37}\! \left(x \right)+F_{45}\! \left(x \right)\\ F_{45}\! \left(x \right) &= F_{46}\! \left(x \right) F_{9}\! \left(x \right)\\ F_{46}\! \left(x \right) &= F_{47}\! \left(x \right)+F_{48}\! \left(x \right)\\ F_{47}\! \left(x \right) &= F_{42}\! \left(x \right)\\ F_{48}\! \left(x \right) &= F_{44}\! \left(x \right)\\ F_{49}\! \left(x \right) &= F_{50}\! \left(x \right) F_{9}\! \left(x \right)\\ F_{50}\! \left(x \right) &= F_{51}\! \left(x \right)+F_{53}\! \left(x \right)\\ F_{51}\! \left(x \right) &= F_{52}\! \left(x \right)\\ F_{52}\! \left(x \right) &= F_{7}\! \left(x \right) F_{9}\! \left(x \right)\\ F_{53}\! \left(x \right) &= 2 F_{17}\! \left(x \right)+F_{49}\! \left(x \right)+F_{54}\! \left(x \right)\\ F_{54}\! \left(x \right) &= F_{55}\! \left(x \right) F_{9}\! \left(x \right)\\ F_{55}\! \left(x \right) &= F_{56}\! \left(x \right)\\ F_{56}\! \left(x \right) &= F_{57}\! \left(x \right) F_{9}\! \left(x \right)\\ F_{57}\! \left(x \right) &= F_{55}\! \left(x \right)+F_{7}\! \left(x \right)\\ F_{58}\! \left(x \right) &= F_{59}\! \left(x \right) F_{9}\! \left(x \right)\\ F_{59}\! \left(x \right) &= F_{60}\! \left(x \right)+F_{7}\! \left(x \right)\\ F_{60}\! \left(x \right) &= F_{17}\! \left(x \right)+F_{58}\! \left(x \right)+F_{61}\! \left(x \right)\\ F_{61}\! \left(x \right) &= F_{62}\! \left(x \right) F_{9}\! \left(x \right)\\ F_{62}\! \left(x \right) &= F_{60}\! \left(x \right)+F_{7}\! \left(x \right)\\ F_{63}\! \left(x \right) &= F_{64}\! \left(x \right)\\ F_{64}\! \left(x \right) &= F_{65}\! \left(x , 1\right)\\ F_{65}\! \left(x , y\right) &= F_{66}\! \left(x , y\right)\\ F_{66}\! \left(x , y\right) &= F_{67}\! \left(x , y\right)\\ F_{67}\! \left(x , y\right) &= F_{68}\! \left(x , y\right) F_{77}\! \left(x , y\right) F_{9}\! \left(x \right)\\ F_{68}\! \left(x , y\right) &= F_{69}\! \left(x , y\right)+F_{87}\! \left(x , y\right)\\ F_{69}\! \left(x , y\right) &= F_{59}\! \left(x \right)+F_{70}\! \left(x , y\right)\\ F_{70}\! \left(x , y\right) &= F_{71}\! \left(x , y\right)+F_{78}\! \left(x , y\right)\\ F_{71}\! \left(x , y\right) &= F_{72}\! \left(x , y\right)\\ F_{72}\! \left(x , y\right) &= F_{73}\! \left(x , y\right) F_{9}\! \left(x \right)\\ F_{73}\! \left(x , y\right) &= F_{71}\! \left(x , y\right)+F_{74}\! \left(x , y\right)\\ F_{74}\! \left(x , y\right) &= F_{75}\! \left(x , y\right)\\ F_{75}\! \left(x , y\right) &= F_{76}\! \left(x , y\right) F_{77}\! \left(x , y\right)\\ F_{76}\! \left(x , y\right) &= y x\\ F_{77}\! \left(x , y\right) &= F_{1}\! \left(x \right)+F_{74}\! \left(x , y\right)\\ F_{78}\! \left(x , y\right) &= 2 F_{17}\! \left(x \right)+F_{79}\! \left(x , y\right)+F_{86}\! \left(x , y\right)\\ F_{79}\! \left(x , y\right) &= F_{80}\! \left(x , y\right) F_{9}\! \left(x \right)\\ F_{80}\! \left(x , y\right) &= F_{78}\! \left(x , y\right)+F_{81}\! \left(x , y\right)\\ F_{81}\! \left(x , y\right) &= F_{17}\! \left(x \right)+F_{82}\! \left(x , y\right)+F_{84}\! \left(x , y\right)\\ F_{82}\! \left(x , y\right) &= F_{76}\! \left(x , y\right) F_{83}\! \left(x , y\right)\\ F_{83}\! \left(x , y\right) &= F_{7}\! \left(x \right)+F_{81}\! \left(x , y\right)\\ F_{84}\! \left(x , y\right) &= F_{85}\! \left(x , y\right) F_{9}\! \left(x \right)\\ F_{85}\! \left(x , y\right) &= F_{74}\! \left(x , y\right)+F_{81}\! \left(x , y\right)\\ F_{86}\! \left(x , y\right) &= F_{70}\! \left(x , y\right) F_{9}\! \left(x \right)\\ F_{87}\! \left(x , y\right) &= \frac{F_{66}\! \left(x , y\right) y -F_{66}\! \left(x , 1\right)}{-1+y}\\ \end{align*}\)