A005558 - cp's OEIS frontend

A005558 a(n) is the number of n-step walks on square lattice such that 0 <= y <= x at each step.

n	a(n)
0	1
1	1
2	3
3	6
4	20
5	50
6	175
7	490
8	1764
9	5292
10	19404
11	60984
12	226512
13	736164
14	2760615
15	9202050
16	34763300
17	118195220
18	449141836
19	1551580888
20	5924217936
21	20734762776
22	79483257308
23	281248448936
24	1081724803600
25	3863302870000
26	14901311070000
27	53644719852000

[1, 1, 3, 6, 20, 50, 175, 490, 1764, 5292, 19404, 60984, 226512, 736164, 2760615, 9202050, 34763300, 118195220, 449141836, 1551580888, 5924217936, 20734762776, 79483257308, 281248448936, 1081724803600, 3863302870000, 14901311070000, 53644719852000]

cp's OEIS Frontend

A005558 a(n) is the number of n-step walks on square lattice such that 0 <= y <= x at each step.

Table of values

List of values