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 A177472 #10 Oct 05 2024 00:23:32 %S A177472 1,1,2,6,18,71,322,1665,9789,64327,468914,3748920,32699022,308710917, %T A177472 3138821688,34186918427,397173376849,4902547569617,64073734206528, %U A177472 883940288032392,12836250526983672,195724485831901029,3126468139092090818,52211816154041174670,909843384081141844312 %N A177472 Number of permutations of order n avoiding the consecutive pattern 11'2'2. %C A177472 To avoid 11'2'2 means not to have four consecutive letters such that the first letter is less than the last one, and the second letter is less than the third one. %H A177472 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. %Y A177472 Cf. A117156, A177470, A177471, A177473, A177475, A177476, A177477, A177478, A177479, A177480, A177481, A177482, A177483, A177484, A376694. %K A177472 nonn %O A177472 0,3 %A A177472 Signy Olafsdottir (signy06(AT)ru.is), May 09 2010 %E A177472 Edited and terms a(0), a(10)-a(24) added by _Max Alekseyev_, Oct 02 2024