regular 15-gon, side 1; trajectories parallel to the side X_0 X_14; one trajectory in each strip
strip j lies between the diagonals X_{j-1}X_{n-j} and X_jX_{n-1-j}; start at 1/3 of the side X_{j-1}X_j, direction east
 j | segments of the simple preclosed part | rotation index s | order of s in Z/n | segments of the closed trajectory | preclosed length | closed length / preclosed length
 1 |   2 |   4 |  15 |   30 | 3.827090915 = 2cos(pi/n) sin(2pi/n)/sin(pi/n) | 15
 2 |   2 |   8 |  15 |   30 | 6.992443043 = 2cos(pi/n) sin(4pi/n)/sin(pi/n) | 15
 3 |   2 |  12 |   5 |   10 | 8.948738245 = 2cos(pi/n) sin(6pi/n)/sin(pi/n) | 5
 4 |   2 |   1 |  15 |   30 | 9.357715307 = 2cos(pi/n) sin(8pi/n)/sin(pi/n) | 15
 5 |   2 |   5 |   3 |    6 | 8.148658380 = 2cos(pi/n) sin(10pi/n)/sin(pi/n) | 3
 6 |   2 |   9 |   5 |   10 | 5.530624392 = 2cos(pi/n) sin(12pi/n)/sin(pi/n) | 5
 7 |   2 |  13 |  15 |   30 | 1.956295201 = 2cos(pi/n) sin(14pi/n)/sin(pi/n) | 15
factors d_j (closed length / preclosed length): [15, 15, 5, 15, 3, 5, 15]
their greatest common divisor: 1  -> reduced factors: [15, 15, 5, 15, 3, 5, 15]
a reduced factor equals n: True
