A108440 - cp's OEIS frontend

A108440 Triangle read by rows: T(n,k) is number of paths from (0,0) to (3n,0) that stay in the first quadrant (but may touch the horizontal axis), consisting of steps u=(2,1), U=(1,2), or d=(1,-1) and having k u=(2,1) steps among the steps leading to the first d step.

n	a(n)
0	1
1	1
2	1
3	5
4	4
5	1
6	33
7	25
8	7
9	1
10	249
11	184
12	54
13	10
14	1
15	2033
16	1481
17	446
18	92
19	13
20	1
21	17485
22	12620
23	3863
24	846
25	139
26	16
27	1
28	156033
29	111889
30	34637
31	7881
32	1411
33	195
34	19
35	1
36	1431281
37	1021424
38	318812
39	74492
40	14102
41	2168
42	260
43	22
44	1
45	13412193
46	9536113
47	2995228

[1, 1, 1, 5, 4, 1, 33, 25, 7, 1, 249, 184, 54, 10, 1, 2033, 1481, 446, 92, 13, 1, 17485, 12620, 3863, 846, 139, 16, 1, 156033, 111889, 34637, 7881, 1411, 195, 19, 1, 1431281, 1021424, 318812, 74492, 14102, 2168, 260, 22, 1, 13412193, 9536113, 2995228]

cp's OEIS Frontend

A108440 Triangle read by rows: T(n,k) is number of paths from (0,0) to (3n,0) that stay in the first quadrant (but may touch the horizontal axis), consisting of steps u=(2,1), U=(1,2), or d=(1,-1) and having k u=(2,1) steps among the steps leading to the first d step.

Table of values

List of values