A333971 - cp's OEIS frontend

A333971 a(n) is the number of semi-meanders with n top arches that have at least one arch with length 1 adjacent to the center of the top arch configuration or at either end of the arch configuration.

n	a(n)
2	1
3	2
4	4
5	8
6	24
7	56
8	168
9	432
10	1320
11	3608
12	11216
13	31952
14	100720
15	295600
16	942272
17	2828112
18	9097256
19	27785112
20	90048656
21	278899152
22	909566560
23	2849498656
24	9342566152
25	29548420688
26	97323261664

[1, 2, 4, 8, 24, 56, 168, 432, 1320, 3608, 11216, 31952, 100720, 295600, 942272, 2828112, 9097256, 27785112, 90048656, 278899152, 909566560, 2849498656, 9342566152, 29548420688, 97323261664]

cp's OEIS Frontend

A333971 a(n) is the number of semi-meanders with n top arches that have at least one arch with length 1 adjacent to the center of the top arch configuration or at either end of the arch configuration.

Table of values

List of values