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 A101900 #11 Jul 28 2018 11:33:56
%S A101900 1,-1,1,-2,5,-17,71,-357,2101,-14203,108609,-927961,8769087,-90874197,
%T A101900 1025292311,-12516360103,164433702745,-2313858448075,34730232119381,
%U A101900 -553983478001961,9359820238735507,-167004393073794933,3138414712193291915,-61966152586833353847
%N A101900 Column 0 of triangular matrix A101897, in which column k equals column 0 of A101897^(k+1) and where the n-th row sums are zero for n>0.
%C A101900 |a(n)| is the number of n-length permutations avoiding the dotted pattern 23\dot{1}(conjectured). - _Michael D. Weiner_, Jul 26 2018
%H A101900 Isak Hilmarsson, Ingibjorg Jonsdottir, Steinunn Sigurdardottir and Sigridur Vidarsdottir, <a href="http://hdl.handle.net/1946/9181">Wilf-classification of mesh patterns of short length</a>, Reykjavík University, Thesis, May 2011.
%H A101900 Isak Hilmarsson, Ingibjorg Jonsdottir, Steinunn Sigurdardottir and Sigridur Vidarsdottir, <a href="http://www.combinatorics.org/ojs/index.php/eljc/article/view/v22i4p13">Wilf-classification of mesh patterns of short length</a>, The Electronic Journal of Combinatorics, Volume 22, Issue 4 (2015).
%Y A101900 Cf. A101897, A101898, A101899, A101901.
%K A101900 sign
%O A101900 0,4
%A A101900 _Paul D. Hanna_, Dec 20 2004