A337703 Irregular table read by rows: Place two n-gons with radii 1 and 2 concentrically, forming an annular area between them. Connect all the vertices with line segments that lie entirely within that area. Then T(n,k) = number of k-sided polygons in that figure for k>=3.

12, 16, 20, 24, 42, 21, 48, 24, 153, 153, 9, 170, 170, 10, 209, 143, 33, 216, 192, 351, 338, 65, 13, 350, 420, 42, 14, 690, 1230, 150, 15, 864, 1088, 240, 16, 16, 935, 1088, 323, 17, 1062, 1026, 234, 18, 1482, 1615, 608, 57, 1660, 1560, 640, 80, 20, 2226, 4494

Offset

1,1

Comments

Because of symmetry, T(n,k) is divisible by n.

See A337700 for illustrations.

Links

Lars Blomberg, Table of n, a(n) for n = 1..678 (rows 3-102)

Example

Table begins:
12
16
20
24
42,21
48,24
153,153,9
170,170,10
209,143,33
216,192
351,338,65,13
350,420,42,14
690,1230,150,15
864,1088,240,16,16
935,1088,323,17
1062,1026,234,18
1482,1615,608,57
1660,1560,640,80,20

Crossrefs

Row sums are A337700. Cf. A337701, A337702.

Sequence in context: A210577 A231903 A364405 * A337700 A243538 A183052

Adjacent sequences: A337700 A337701 A337702 * A337704 A337705 A337706

Keyword

nonn,tabf

Author

Lars Blomberg, Sep 16 2020

Status

approved