A108428 - cp's OEIS frontend

A108428 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 have k doubledescents (i.e., dd's).

n	a(n)
0	1
1	1
2	1
3	1
4	4
5	4
6	1
7	1
8	9
9	23
10	23
11	9
12	1
13	1
14	16
15	76
16	156
17	156
18	76
19	16
20	1
21	1
22	25
23	190
24	650
25	1167
26	1167
27	650
28	190
29	25
30	1
31	1
32	36
33	400
34	2045
35	5685
36	9318
37	9318
38	5685
39	2045
40	400
41	36
42	1
43	1
44	49
45	749
46	5341
47	21133
48	50813
49	77947
50	77947
51	50813
52	21133
53	5341
54	749
55	49
56	1
57	1
58	64
59	1288

[1, 1, 1, 1, 4, 4, 1, 1, 9, 23, 23, 9, 1, 1, 16, 76, 156, 156, 76, 16, 1, 1, 25, 190, 650, 1167, 1167, 650, 190, 25, 1, 1, 36, 400, 2045, 5685, 9318, 9318, 5685, 2045, 400, 36, 1, 1, 49, 749, 5341, 21133, 50813, 77947, 77947, 50813, 21133, 5341, 749, 49, 1, 1, 64, 1288]

cp's OEIS Frontend

A108428 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 have k doubledescents (i.e., dd's).

Table of values

List of values