A334640 - cp's OEIS frontend

A334640 a(n) is the total number of down steps between the 2nd and 3rd up steps in all 2-Dyck paths of length 3*n. A 2-Dyck path is a nonnegative lattice path with steps (1, 2), (1, -1) that starts and ends at y = 0.

n	a(n)
0	0
1	0
2	9
3	19
4	72
5	324
6	1595
7	8307
8	44982
9	250648
10	1427679
11	8274825
12	48644310
13	289334160
14	1738043892
15	10529070020
16	64252519830
17	394601627376
18	2437058926871
19	15126463230165
20	94306717535940
21	590318477063700
22	3708527622652755
23	23374587898663155
24	147770791807427880

[0, 0, 9, 19, 72, 324, 1595, 8307, 44982, 250648, 1427679, 8274825, 48644310, 289334160, 1738043892, 10529070020, 64252519830, 394601627376, 2437058926871, 15126463230165, 94306717535940, 590318477063700, 3708527622652755, 23374587898663155, 147770791807427880]

cp's OEIS Frontend

A334640 a(n) is the total number of down steps between the 2nd and 3rd up steps in all 2-Dyck paths of length 3*n. A 2-Dyck path is a nonnegative lattice path with steps (1, 2), (1, -1) that starts and ends at y = 0.

Table of values

List of values