A108442 - cp's OEIS frontend

A108442 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 only u steps among the steps leading to the first d step.

n	a(n)
0	1
1	1
2	3
3	15
4	97
5	721
6	5827
7	49759
8	441729
9	4035937
10	37702723
11	358474735
12	3457592161
13	33748593841
14	332730216579
15	3308635650495
16	33145196426753
17	334193815799233
18	3388807714823043
19	34537227997917391
20	353578650475659617
21	3634495706671023505
22	37496621681376849219
23	388135791657414454815

[1, 1, 3, 15, 97, 721, 5827, 49759, 441729, 4035937, 37702723, 358474735, 3457592161, 33748593841, 332730216579, 3308635650495, 33145196426753, 334193815799233, 3388807714823043, 34537227997917391, 353578650475659617, 3634495706671023505, 37496621681376849219, 388135791657414454815]

cp's OEIS Frontend

A108442 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 only u steps among the steps leading to the first d step.

Table of values

List of values