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.

4, 36, 1240, 73240, 7171176, 1016813448, 198480110880, 50752206180576, 16460660622560680, 6595414427636900536, 3198428240666246044704, 1845848150787599809368856, 1250049326783769438348496480, 981653074459964543314138858320

Offset: 2

Author

Ludovic Schwob, Mar 29 2024

Keywords

• nonn

Comments

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).

Links

• Ludovic Schwob, Illustration of a(3)

Crossrefs

Cf. A365094, A295264,

Formula

a(n) is always divisible by 2*n, because the considered cycles cannot have rotational symmetry.