A045723 - cp's OEIS frontend

A045723 Number of configurations, excluding reflections and black-white interchanges, of n black and n white beads on a string.

n	a(n)
0	1
1	1
2	3
3	7
4	23
5	71
6	252
7	890
8	3299
9	12283
10	46508
11	176870
12	677294
13	2602198
14	10034104
15	38787572
16	150289699
17	583434323
18	2268861516
19	8836447022
20	34461940538
21	134564992898
22	526025965864
23	2058359779052
24	8061905791118
25	31602659998046

[1, 1, 3, 7, 23, 71, 252, 890, 3299, 12283, 46508, 176870, 677294, 2602198, 10034104, 38787572, 150289699, 583434323, 2268861516, 8836447022, 34461940538, 134564992898, 526025965864, 2058359779052, 8061905791118, 31602659998046]

cp's OEIS Frontend

A045723 Number of configurations, excluding reflections and black-white interchanges, of n black and n white beads on a string.

Table of values

List of values