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 A060148 #29 Feb 03 2025 14:03:52 %S A060148 1,1,3,15,97,733,6147,55541,530773,5298723,54780831,582817337, %T A060148 6350647873,70614662303,798935833885,9176290300419,106793746090045, %U A060148 1257408517909283,14958873368871405,179614516459970349,2174717049372338913,26530091641879493297,325875790867387681293 %N A060148 Number of closed forest meander systems with 2n crossings. %C A060148 A forest meander system is a meander system that does not have any components which are entirely enclosed by another. - _Andrew Howroyd_, Nov 22 2015 %C A060148 The components of a forest meander system do not necessarily all have exterior arches. See example. Those that do are called tame (A060066). - _Andrew Howroyd_, Feb 02 2025 %H A060148 Roland Bacher, <a href="http://www-fourier.ujf-grenoble.fr/sites/default/files/ref_478.pdf">Meander algebras</a> %F A060148 1 <= A060066(n) <= a(n) <= A060174(n) <= A060198(n) <= 16^n. - _Andrew Howroyd_, Feb 02 2025 %e A060148 An example of a 2 component forest meander system with 8 crossings that is not tame: %e A060148 ________ %e A060148 / ______ \ %e A060148 / / \ \ %e A060148 / / /\ /\ \ \ %e A060148 \ \ \/ / / \/ %e A060148 \ \__/ / %e A060148 \____/ %Y A060148 Row sums of A380368. %Y A060148 Meander sequences in Bacher's paper: A005315, A060066, A060089, A060111, A060148, A060149, A060174, A060198, A060206. %K A060148 nonn,nice %O A060148 0,3 %A A060148 _N. J. A. Sloane_, Apr 10 2001 %E A060148 More terms from _Sascha Kurz_, Mar 25 2002 %E A060148 a(15)-a(20) from _Andrew Howroyd_, Nov 22 2015 %E A060148 a(0)=1 prepended and a(21)-a(22) from _Andrew Howroyd_, Jan 31 2025