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%I #18 Oct 02 2024 04:16:06
%S 1,1,2,6,18,70,300,1435,7910,47376,316008,2314158,18331236,158024724,
%T 1462752720,14497475850,153488070450,1724035906450,20515906356660,
%U 257720354712106,3406481187714176,47293781230517640,687760952277462336,10456003715906638162,165890170459303164420
%N Number of permutations of order n avoiding the consecutive pattern 11'22'.
%C To avoid 11'22' means not to have four consecutive letters such that the first letter is less than the third one and the second letter is less than the fourth one.
%H S. Kitaev, <a href="https://doi.org/10.1016/j.dam.2006.09.011">Introduction to partially ordered patterns</a>, Discrete Applied Mathematics 155 (2007), 929-944.
%H Rémy Sigrist, <a href="/A177470/a177470.txt">C program</a>
%o (C) // See Links section.
%Y Cf. A117156, A177471, A177472, A177473, A177475, A177476, A177477, A177478, A177479, A177480, A177481, A177482, A177483, A177484, A376694.
%K nonn
%O 0,3
%A Signy Olafsdottir (signy06(AT)ru.is), May 09 2010
%E a(0) = 1 and a(10)-a(16) from _Rémy Sigrist_, Mar 13 2023
%E Edited and a(17)-a(24) added by _Max Alekseyev_, Oct 01 2024