A067311 - cp's OEIS frontend

A067311 Triangle read by rows: T(n,k) gives number of ways of arranging n chords on a circle with k simple intersections (i.e., no intersections with 3 or more chords) - positive values only.

n	a(n)
0	1
1	1
2	2
3	1
4	5
5	6
6	3
7	1
8	14
9	28
10	28
11	20
12	10
13	4
14	1
15	42
16	120
17	180
18	195
19	165
20	117
21	70
22	35
23	15
24	5
25	1
26	132
27	495
28	990
29	1430
30	1650
31	1617
32	1386
33	1056
34	726
35	451
36	252
37	126
38	56
39	21
40	6
41	1
42	429
43	2002
44	5005
45	9009
46	13013
47	16016
48	17381
49	16991
50	15197
51	12558
52	9646
53	6916
54	4641
55	2912
56	1703
57	924
58	462
59	210
60	84
61	28
62	7
63	1

[1, 1, 2, 1, 5, 6, 3, 1, 14, 28, 28, 20, 10, 4, 1, 42, 120, 180, 195, 165, 117, 70, 35, 15, 5, 1, 132, 495, 990, 1430, 1650, 1617, 1386, 1056, 726, 451, 252, 126, 56, 21, 6, 1, 429, 2002, 5005, 9009, 13013, 16016, 17381, 16991, 15197, 12558, 9646, 6916, 4641, 2912, 1703, 924, 462, 210, 84, 28, 7, 1]

cp's OEIS Frontend

A067311 Triangle read by rows: T(n,k) gives number of ways of arranging n chords on a circle with k simple intersections (i.e., no intersections with 3 or more chords) - positive values only.

Table of values

List of values