A145601 - cp's OEIS frontend

A145601 a(n) is the number of walks from (0,0) to (0,2) that remain in the upper half-plane y >= 0 using 2*n unit steps either up (U), down (D), left (L) or right (R).

n	a(n)
1	1
2	15
3	189
4	2352
5	29700
6	382239
7	5010005
8	66745536
9	901995588
10	12342120700
11	170724392916
12	2384209771200
13	33577620944400
14	476432168185575
15	6805332732133125
16	97790670976838400
17	1412830549632694500

[1, 15, 189, 2352, 29700, 382239, 5010005, 66745536, 901995588, 12342120700, 170724392916, 2384209771200, 33577620944400, 476432168185575, 6805332732133125, 97790670976838400, 1412830549632694500]

cp's OEIS Frontend

A145601 a(n) is the number of walks from (0,0) to (0,2) that remain in the upper half-plane y >= 0 using 2*n unit steps either up (U), down (D), left (L) or right (R).

Table of values

List of values