The conjectured enumeration of alternating involutions avoiding 1432 and 3214

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Let AIn(ρ)AI_n(\rho) and RAIn(ρ)RAI_n(\rho) denote, respectively, the sets of alternating and reverse alternating involutions of length nn avoiding the pattern ρ\rho, and let MnM_n be the sequence used in the paper. The 1432–3214 enumeration conjecture.

∣AI2n(1432)∣=∣AI2n(3214)∣=∣RAI2n(1432)∣=∣RAI2n(3214)∣=Mn,|AI_{2n}(1432)|=|AI_{2n}(3214)|=|RAI_{2n}(1432)|=|RAI_{2n}(3214)|=M_n, ∣AI2n+1(1432)∣=∣RAI2n+1(3214)∣=Mn,|AI_{2n+1}(1432)|=|RAI_{2n+1}(3214)|=M_n, ∣AI2n−1(3214)∣=∣RAI2n−1(1432)∣=Mn−Mn−2.|AI_{2n-1}(3214)|=|RAI_{2n-1}(1432)|=M_n-M_{n-2}.

The paper presents these equalities as conjectures based on numerical evidence, covering the patterns 1432 and 3214.

References

Primary source

Marilena Barnabei, Flavio Bonetti, Niccolò Castronuovo and Matteo Silimbani, “Pattern avoiding alternating involutions”, arXiv:2206.13877 (2022).

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