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A358328
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.
1
0, 0, 1, 1, 0, 1, 4, 4, 4, 2, 98, 120, 84, 24, 6, 5648, 6912, 4032, 1344, 288, 40, 532344, 631680, 351360, 118408, 26400, 3840, 322, 72724122, 84211200, 45907200, 15436800, 3513600, 552960, 57600, 3294, 13577195574, 15432560640, 8305920000, 2786273280, 643507200, 106122240, 12418560, 967680, 40320
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, 4, 4, 2;
98, 120, 84, 24, 6;
CROSSREFS
Row sums give A094155(n).
Cf. A330662.
Sequence in context: A105724 A063448 A232526 * A117499 A063570 A023977
KEYWORD
nonn,tabl
AUTHOR
Ludovic Schwob, Nov 09 2022
STATUS
approved