A108427 - cp's OEIS frontend

A108427 Number of peaks of the form Ud in all 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).

n	a(n)
1	1
2	9
3	85
4	833
5	8361
6	85305
7	880685
8	9173505
9	96220561
10	1014889769
11	10753517061
12	114375683009
13	1220435354425
14	13058529727833
15	140059477112925
16	1505357362548737
17	16209464357137953
18	174827809500822345
19	1888383038494338485
20	20424130116241366593
21	221164921352046545609
22	2397512484385887298681

[1, 9, 85, 833, 8361, 85305, 880685, 9173505, 96220561, 1014889769, 10753517061, 114375683009, 1220435354425, 13058529727833, 140059477112925, 1505357362548737, 16209464357137953, 174827809500822345, 1888383038494338485, 20424130116241366593, 221164921352046545609, 2397512484385887298681]

cp's OEIS Frontend

A108427 Number of peaks of the form Ud in all 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).

Table of values

List of values