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A372734
Irregular table read by rows: T(n,k) is the number of k-gons, k>=2, among all distinct circles that can be constructed from the 3 vertices and the equally spaced 3*n points placed on the sides of an equilateral triangle when every pair of the 3 + 3*n points are connected by a circle and where the points lie at the ends of the circle's diameter.
4
0, 7, 12, 61, 9, 6, 6, 303, 108, 9, 9, 3, 18, 771, 603, 150, 15, 9, 0, 1, 24, 1722, 1740, 339, 81, 3, 0, 1, 30, 3789, 4326, 1104, 234, 18, 3, 36, 6907, 8274, 2193, 432, 45, 18, 66, 12012, 15504, 4173, 922, 105, 45, 3, 3, 90, 19860, 24774, 7389, 1773, 150, 30, 48, 30594, 39852, 12438, 2998, 387, 48
OFFSET
0,2
COMMENTS
A circle is constructed for every pair of the 3 + 3*n points, the two points lying at the ends of a diameter of the circle.
See A372731 and A372732 for images of the circles.
FORMULA
Sum of row(n) = A372732(n).
EXAMPLE
The table begins:
0, 7;
12, 61, 9, 6;
6, 303, 108, 9, 9, 3;
18, 771, 603, 150, 15, 9, 0, 1;
24, 1722, 1740, 339, 81, 3, 0, 1;
30, 3789, 4326, 1104, 234, 18, 3;
36, 6907, 8274, 2193, 432, 45, 18;
66, 12012, 15504, 4173, 922, 105, 45, 3, 3;
90, 19860, 24774, 7389, 1773, 150, 30;
48, 30594, 39852, 12438, 2998, 387, 48;
96, 45456, 59019, 18669, 4429, 609, 93, 3, 6;
90, 66633, 86088, 29136, 6840, 1164, 195, 6;
120, 90210, 121614, 40035, 9160, 1362, 177, 12, 9;
108, 124245, 167646, 57048, 14377, 1989, 300, 33, 15;
.
.
CROSSREFS
Cf. A372731 (vertices), A372732 (regions), A372733 (edges), A372735 (number of circles), A372617, A371376, A361623, A360354.
Sequence in context: A038278 A266056 A083335 * A358782 A119179 A121983
KEYWORD
nonn,tabf
AUTHOR
Scott R. Shannon, May 12 2024
STATUS
approved