A334642 - cp's OEIS frontend

A334642 a(n) is the total number of down steps between the first and second up steps in all 2_1-Dyck paths of length 3*n. A 2_1-Dyck path is a lattice path with steps (1, 2), (1, -1) that starts and ends at y = 0 and stays above the line y = -1.

n	a(n)
0	0
1	3
2	9
3	32
4	139
5	669
6	3430
7	18360
8	101403
9	573551
10	3305445
11	19340100
12	114579348
13	685962172
14	4143459504
15	25220816752
16	154545611355
17	952583230899
18	5902090839715
19	36738469359480
20	229636903762035
21	1440759023752125
22	9070230371741490
23	57278432955350880

[0, 3, 9, 32, 139, 669, 3430, 18360, 101403, 573551, 3305445, 19340100, 114579348, 685962172, 4143459504, 25220816752, 154545611355, 952583230899, 5902090839715, 36738469359480, 229636903762035, 1440759023752125, 9070230371741490, 57278432955350880]

cp's OEIS Frontend

A334642 a(n) is the total number of down steps between the first and second up steps in all 2_1-Dyck paths of length 3*n. A 2_1-Dyck path is a lattice path with steps (1, 2), (1, -1) that starts and ends at y = 0 and stays above the line y = -1.

Table of values

List of values