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 A371611 #8 May 05 2024 08:43:44 %S A371611 4,36,1240,73240,7171176,1016813448,198480110880,50752206180576, %T A371611 16460660622560680,6595414427636900536,3198428240666246044704, %U A371611 1845848150787599809368856,1250049326783769438348496480,981653074459964543314138858320 %N A371611 Number of 2*n-sided cycles with the property that one makes the same number of left and right turns while following its edges. %C A371611 Cycles that differ by rotation or reflection are counted separately. By "n-sided cycles" we mean the cycles that can be drawn by connecting n equally spaced points on a circle (possibly self-intersecting). %H A371611 Ludovic Schwob, <a href="/A371611/a371611.pdf">Illustration of a(3)</a> %F A371611 a(n) is always divisible by 2*n, because the considered cycles cannot have rotational symmetry. %Y A371611 Cf. A365094, A295264, %K A371611 nonn %O A371611 2,1 %A A371611 _Ludovic Schwob_, Mar 29 2024