%I #13 Mar 07 2020 21:28:52
%S 1,4,17,66,254,956,3584,13256,49052,179552,658560,2394504,8724464,
%T 31575096,114451388,412811544,1490190544,5360943684,19288139802,
%U 69245171564,248463024330,890477645192,3188033497580,11409453277272,40771092374710,145735210316376,519955750491512
%N Number of semi-meanders of order n with 4 components.
%H Andrew Howroyd, <a href="/A046723/b046723.txt">Table of n, a(n) for n = 4..40</a>
%H P. Di Francesco, O. Golinelli and E. Guitter, <a href="http://arXiv.org/abs/hep-th/9506030">Meander, folding and arch statistics</a>, arXiv:hep-th/9506030, 1995.
%Y Cf. A000682, A046726.
%K nonn
%O 4,2
%A _N. J. A. Sloane_
%E a(15)-a(40) from _Andrew Howroyd_, Dec 07 2015