A108439 - cp's OEIS frontend

A108439 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 abscissa of first return equal to 3k.

n	a(n)
1	2
2	4
3	6
4	20
5	12
6	34
7	132
8	60
9	68
10	238
11	996
12	396
13	340
14	476
15	1858
16	8132
17	2988
18	2244
19	2380
20	3716
21	15510
22	69940
23	24396
24	16932
25	15708
26	18580
27	31020
28	135490
29	624132
30	209820
31	138244
32	118524
33	122628
34	155100
35	270980
36	1223134
37	5725124
38	1872396
39	1188980

[2, 4, 6, 20, 12, 34, 132, 60, 68, 238, 996, 396, 340, 476, 1858, 8132, 2988, 2244, 2380, 3716, 15510, 69940, 24396, 16932, 15708, 18580, 31020, 135490, 624132, 209820, 138244, 118524, 122628, 155100, 270980, 1223134, 5725124, 1872396, 1188980]

cp's OEIS Frontend

A108439 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 abscissa of first return equal to 3k.

Table of values

List of values