cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A340568 Total number of consecutive triples matching the pattern 132 in all faro permutations of length n.

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%I A340568 #14 Jan 11 2021 23:17:17
%S A340568 0,0,0,1,4,10,28,61,152,318,748,1538,3496,7124,15832,32093,70192,
%T A340568 141814,306508,617878,1323272,2663340,5662600,11383986,24061264,
%U A340568 48330540,101653368,204049636,427414672,857503784,1789891888,3589478621,7469802592,14974962854,31081371148
%N A340568 Total number of consecutive triples matching the pattern 132 in all faro permutations of length n.
%C A340568 Faro permutations are permutations avoiding the three consecutive patterns 231, 321 and 312. They are obtained by a perfect faro shuffle of two nondecreasing words of lengths differing by at most one. Also the popularity of consecutive pattern 213.
%H A340568 Jean-Luc Baril, Alexander Burstein, and Sergey Kirgizov, <a href="https://arxiv.org/abs/2010.06270">Pattern statistics in faro words and permutations</a>, arXiv:2010.06270 [math.CO], 2020. See Table 1.
%F A340568 G.f.: x*(-1+4*x^2+2*x+(1-2*x)*sqrt(1-4*x^2)) / ((1-2*x)*(1+sqrt(1-4*x^2))*sqrt(1-4*x^2)).
%e A340568 For n = 4, there are 6 faro permutations: 1234, 1243, 1324, 2134, 2143, 3142. They contain in total 4 consecutive patterns 132 and also 4 consecutive patterns 213.
%o A340568 (PARI) seq(n)={my(t=sqrt(1-4*x^2+O(x^n))); Vec(x*(-1+4*x^2+2*x+(1-2*x)*t) / ((1-2*x)*(1+t)*t), -(1+n))} \\ _Andrew Howroyd_, Jan 11 2021
%Y A340568 A001405 counts faro permutations of length n.
%Y A340568 Cf. A107373, A340567, A340569.
%K A340568 nonn
%O A340568 0,5
%A A340568 _Sergey Kirgizov_, Jan 11 2021