A337581 - cp's OEIS frontend

A337581 a(n) is the number of semi-meanders with n top arches that have both an arch of length 1 adjacent to the center of the top arch configuration and an arch of length 1 starting or ending the top arch configuration.

n	a(n)
2	1
3	2
4	4
5	8
6	16
7	40
8	96
9	264
10	696
11	2016
12	5624
13	16840
14	48792
15	149512
16	445112
17	1387384
18	4215496
19	13312752
20	41097864
21	131146520
22	410045672
23	1319612232
24	4169110888
25	13511677040
26	43060097728
27	140383359392

[1, 2, 4, 8, 16, 40, 96, 264, 696, 2016, 5624, 16840, 48792, 149512, 445112, 1387384, 4215496, 13312752, 41097864, 131146520, 410045672, 1319612232, 4169110888, 13511677040, 43060097728, 140383359392]

cp's OEIS Frontend

A337581 a(n) is the number of semi-meanders with n top arches that have both an arch of length 1 adjacent to the center of the top arch configuration and an arch of length 1 starting or ending the top arch configuration.

Table of values

List of values