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 A224240 #14 Apr 07 2021 12:22:36 %S A224240 1,8,34,142,596,2530,10842,46766,202594,880210 %N A224240 Number of rationally smooth Schubert varieties of type B_n. %C A224240 Also, the number of signed permutations w in the hyperoctahedral group whose initial interval [id,w] in Bruhat order is rank symmetric. Equivalently, the Kazhdan-Lusztig polynomial P_id,w(q) = 1. Characterized by pattern avoidance. %D A224240 S. Billey, Pattern avoidance and rational smoothness of Schubert varieties, Advances in Math, vol. 139 (1998) pp. 141-156. %Y A224240 Cf. A061539. %K A224240 nonn,hard,more %O A224240 1,2 %A A224240 _Sara Billey_, Apr 01 2013