A118921 - cp's OEIS frontend

A118921 Triangle read by rows: T(n,k) is the number of Grand Dyck paths of semilength n having first return to the x-axis at (2k,0) (n,k >= 1). (A Grand Dyck path of semilength n is a path in the half-plane x >= 0, starting at (0,0), ending at (2n,0) and consisting of steps u=(1,1) and d=(1,-1)).

n	a(n)
1	2
2	4
3	2
4	12
5	4
6	4
7	40
8	12
9	8
10	10
11	140
12	40
13	24
14	20
15	28
16	504
17	140
18	80
19	60
20	56
21	84
22	1848
23	504
24	280
25	200
26	168
27	168
28	264
29	6864
30	1848
31	1008
32	700
33	560
34	504
35	528
36	858
37	25740
38	6864
39	3696
40	2520
41	1960
42	1680
43	1584
44	1716
45	2860
46	97240
47	25740
48	13728
49	9240
50	7056
51	5880
52	5280

[2, 4, 2, 12, 4, 4, 40, 12, 8, 10, 140, 40, 24, 20, 28, 504, 140, 80, 60, 56, 84, 1848, 504, 280, 200, 168, 168, 264, 6864, 1848, 1008, 700, 560, 504, 528, 858, 25740, 6864, 3696, 2520, 1960, 1680, 1584, 1716, 2860, 97240, 25740, 13728, 9240, 7056, 5880, 5280]

cp's OEIS Frontend

A118921 Triangle read by rows: T(n,k) is the number of Grand Dyck paths of semilength n having first return to the x-axis at (2k,0) (n,k >= 1). (A Grand Dyck path of semilength n is a path in the half-plane x >= 0, starting at (0,0), ending at (2n,0) and consisting of steps u=(1,1) and d=(1,-1)).

Table of values

List of values