A290447 - cp's OEIS frontend

A290447 Consider n equally spaced points along a line and join every pair of points by a semicircle above the line; a(n) is the number of intersection points.

n	a(n)
1	0
2	0
3	0
4	1
5	5
6	15
7	35
8	70
9	124
10	200
11	300
12	445
13	627
14	875
15	1189
16	1564
17	2006
18	2568
19	3225
20	4035
21	4972
22	6030
23	7250
24	8701
25	10323
26	12156
27	14235
28	16554
29	19124
30	22072
31	25250
32	28863
33	32827
34	37166
35	41949
36	47142
37	52653
38	58794
39	65503
40	72741
41	80437

[0, 0, 0, 1, 5, 15, 35, 70, 124, 200, 300, 445, 627, 875, 1189, 1564, 2006, 2568, 3225, 4035, 4972, 6030, 7250, 8701, 10323, 12156, 14235, 16554, 19124, 22072, 25250, 28863, 32827, 37166, 41949, 47142, 52653, 58794, 65503, 72741, 80437]

cp's OEIS Frontend

A290447 Consider n equally spaced points along a line and join every pair of points by a semicircle above the line; a(n) is the number of intersection points.

Table of values

List of values