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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.
1
4, 36, 1240, 73240, 7171176, 1016813448, 198480110880, 50752206180576, 16460660622560680, 6595414427636900536, 3198428240666246044704, 1845848150787599809368856, 1250049326783769438348496480, 981653074459964543314138858320
OFFSET
2,1
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).
FORMULA
a(n) is always divisible by 2*n, because the considered cycles cannot have rotational symmetry.
CROSSREFS
Sequence in context: A353410 A360725 A173212 * A143764 A152287 A086857
KEYWORD
nonn
AUTHOR
Ludovic Schwob, Mar 29 2024
STATUS
approved