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.
%I A324139 #19 Oct 31 2019 01:31:00
%S A324139 1,1,2,6,24,120,720,5020,39720,350496,3404208,36024468,412029720,
%T A324139 5060178264,66366899712,925327730484,13661323157928,212844811207536,
%U A324139 3489053207930640,60017166553937508,1080783290762095320,20331614843059904712,398783856019074779808,8140910725545925463172
%N A324139 Number of permutations of [n] that avoid the shuffle pattern s-k-t, where s = 132 and t = 132.
%H A324139 Sergey Kitaev, <a href="http://dx.doi.org/10.1016/j.disc.2004.03.017">Partially Ordered Generalized Patterns</a>, Discrete Math. 298 (2005), no. 1-3, 212-229.
%F A324139 Let b(n) = A111004(n) = number of permutations avoiding a consecutive 132 pattern. Then a(n) = Sum_{i = 0..n-1} binomial(n-1,i) (2*b(i)*a(n-1-i) - b(i)*b(n-1-i)) for n >= 1 with a(0) = b(0) = 1. [See the recurrence for C_n on p. 220 of Kitaev (2005).] - _Petros Hadjicostas_, Oct 30 2019
%Y A324139 Cf. A000142, A111004.
%K A324139 nonn
%O A324139 0,3
%A A324139 _N. J. A. Sloane_, Feb 16 2019
%E A324139 More terms from _Petros Hadjicostas_, Oct 30 2019