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 A006246 M0920 #46 Mar 18 2025 16:24:51 %S A006246 1,1,1,2,3,20,242,6405,316835,28627261,4686329954,1382939012729, %T A006246 732955581630129 %N A006246 Number of simple arrangements of pseudolines in the projective plane with an oriented marked cell; number of oriented abstract order types of n points (distinguishing mirror-symmetric copies). %C A006246 Previous name was: Number of primitive sorting networks on n elements. %D A006246 M. H. Klin et al., "2D-configurations and clique-cyclic orientations of the graphs L(K_p)", pages 149-162 of Reports in Molecular Theory, Vol. 1, 1990. %D A006246 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). %H A006246 D. E. Knuth, <a href="https://doi.org/10.1007/3-540-55611-7">Axioms and Hulls</a>, Lect. Notes Comp. Sci., Vol. 606, Springer-Verlag, Berlin, Heidelberg, 1992, p.35, entry C_n. %H A006246 Günter Rote, <a href="https://arxiv.org/abs/2503.02336">NumPSLA — An experimental research tool for pseudoline arrangements and order types</a>, arXiv:2503.02336 [math.CO], 2025. See Table 5 on p. 18:17, last column. %H A006246 <a href="/index/So#sorting">Index entries for sequences related to sorting</a> %Y A006246 Cf. A006245. See A006247 for abstract order types when mirror-symmetric copies are identified. %K A006246 nonn,more %O A006246 1,4 %A A006246 _N. J. A. Sloane_ %E A006246 Definition corrected by _Günter Rote_, Dec 02 2021 %E A006246 a(12) and a(13) from _Günter Rote_, Mar 04 2025