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A358329
Triangle read by rows: T(n,k) is the number of polygons with 2*n sides, of which k run through the center of a circle, on the circumference of which the 2*n vertices of the polygon are arranged at equal spacing, up to rotation and reflection.
1
0, 0, 1, 1, 0, 1, 4, 3, 3, 2, 70, 60, 54, 12, 6, 2980, 3512, 2088, 704, 156, 28, 268444, 315840, 176928, 59204, 13488, 1920, 193, 36387789, 42112416, 22965696, 7722144, 1759104, 277344, 28992, 1743, 6789078267, 7716280320, 4153217280, 1393136640, 321814080, 53061120, 6216960, 483840, 20640
OFFSET
0,7
COMMENTS
By "2*n-sided polygons" we mean the polygons that can be drawn by connecting 2*n equally spaced points on a circle.
T(0,0)=0 and T(0,1)=1 by convention.
The sequence is limited to even-sided polygons, since all odd-sided polygons have no side passing through the center.
LINKS
EXAMPLE
Triangle begins:
0;
0, 1;
1, 0, 1;
4, 3, 3, 2;
70, 60, 54, 12, 6;
CROSSREFS
Row sums give A094157(n).
Cf. A330662.
Sequence in context: A117691 A375311 A243564 * A171627 A239884 A143487
KEYWORD
nonn,tabl
AUTHOR
Ludovic Schwob, Nov 09 2022
STATUS
approved