%I #10 Mar 13 2023 17:48:22
%S 1,1,2,6,18,70,300,1435,7910,47376,316008,2314158,18331236,158024724,
%T 1462752720,14497475850,153488070450
%N Avoiding the pattern 11'22'. 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), 929944.
%H Rémy Sigrist, <a href="/A177470/a177470.txt">C program</a>
%o (C) See Links section.
%Y Cf. A177471A177476.
%K nonn,more
%O 1,3
%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
