A276409 - OEIS

%I #20 Aug 03 2022 10:38:19

%S 1,0,2,2,6,24,44,136,298,914,2462,6464,17740,47840,133618,366162,

%T 1011190,2801144,7775916,21680712,60443514,168963010,472975278,

%U 1326349568,3725180524,10475012672,29494512354,83141905570,234634612198,662840458840,1874315939756

%N Number of reduced words of length n in the alphabet {U,U^(-1),S,S^(-1)} that are equal to unity if U^3 = S^2 = 1.

%H G. Alkauskas, <a href="http://arxiv.org/abs/1512.02596">The modular group and words in its two generators</a>, arXiv:1512.02596 [math.NT], 2015-2017.

%H G. Alkauskas, <a href="https://doi.org/10.1007/s10986-017-9339-2">The modular group and words in its two generators</a>, Lithuanian Math. J. 57(1) (2017), 1-12.

%H Jason Bell and Marni Mishna, <a href="https://arxiv.org/abs/1805.08118">On the Complexity of the Cogrowth Sequence</a>, arXiv:1805.08118 [math.CO], 2018.

%Y Cf. A265434, A276408.

%K nonn

%O 0,3

%A _N. J. A. Sloane_, Sep 14 2016

%E Name changed, terms a(12) and beyond added using g.f. from Alkauskas by _Andrey Zabolotskiy_, Aug 03 2022