A306813 - cp's OEIS frontend

A306813 Number of 2n-step paths from (0,0) to (0,n) that stay in the first quadrant (but may touch the axes) consisting of steps (-1,0), (0,1), (0,-1) and (1,-1).

n	a(n)
0	1
1	0
2	3
3	10
4	20
5	237
6	770
7	3944
8	28635
9	112360
10	744084
11	4381083
12	21579779
13	143815322
14	801165187
15	4578481584
16	29176623983
17	165772480380
18	1013147794546
19	6259309820475
20	36974951346176
21	230752749518819
22	1413352914731005
23	8618746801792237
24	53986291171211635

[1, 0, 3, 10, 20, 237, 770, 3944, 28635, 112360, 744084, 4381083, 21579779, 143815322, 801165187, 4578481584, 29176623983, 165772480380, 1013147794546, 6259309820475, 36974951346176, 230752749518819, 1413352914731005, 8618746801792237, 53986291171211635]

cp's OEIS Frontend

A306813 Number of 2n-step paths from (0,0) to (0,n) that stay in the first quadrant (but may touch the axes) consisting of steps (-1,0), (0,1), (0,-1) and (1,-1).

Table of values

List of values