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%I #28 Sep 03 2019 09:56:36
%S 1,2,10,66,504,4210,37378,346846,3328188,32786630,329903058,
%T 3377919260,35095839848,369192702554,3925446804750,42126805350798,
%U 455792943581400,4967158911871358,54480174340453578,600994488311709056,6664356253639465480
%N Number of rotationally symmetric closed meanders of length 4n+2.
%C Closed meanders of other lengths do not have rotational symmetry. - _Andrew Howroyd_, Nov 24 2015
%C See A077460 for additional information on the symmetries of closed meanders.
%H R. Bacher, <a href="http://www-fourier.ujf-grenoble.fr/sites/default/files/ref_478.pdf">Meander algebras</a>
%H Andrew Howroyd, <a href="/A060206/a060206.pdf">Illustration of a(1) and a(2)</a>
%F a(n) = A000682(2n + 1). - _Andrew Howroyd_, Nov 24 2015
%t A000682 = Import["https://oeis.org/A000682/b000682.txt", "Table"][[All, 2]];
%t a[n_] := A000682[[2n + 1]];
%t a /@ Range[0, 20] (* _Jean-François Alcover_, Sep 03 2019 *)
%Y Cf. A000682, A005315, A077055, A077460, A223096.
%Y Meander sequences in Bacher's paper: A060066, A060089, A060111, A060148, A060149, A060174, A060198.
%K nonn,nice
%O 0,2
%A _N. J. A. Sloane_, Apr 10 2001
%E Name edited by _Andrew Howroyd_, Nov 24 2015
%E a(7)-a(20) from _Andrew Howroyd_, Nov 24 2015
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