A108447 - cp's OEIS frontend

A108447 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 have no peaks of the form ud.

n	a(n)
0	1
1	1
2	4
3	20
4	113
5	688
6	4404
7	29219
8	199140
9	1385904
10	9807820
11	70364704
12	510609620
13	3741212535
14	27639233548
15	205660399220
16	1539916433473
17	11594310041792
18	87725707127600
19	666681174728724
20	5086601816592432
21	38948589882247968

[1, 1, 4, 20, 113, 688, 4404, 29219, 199140, 1385904, 9807820, 70364704, 510609620, 3741212535, 27639233548, 205660399220, 1539916433473, 11594310041792, 87725707127600, 666681174728724, 5086601816592432, 38948589882247968]

cp's OEIS Frontend

A108447 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 have no peaks of the form ud.

Table of values

List of values