A247630 - cp's OEIS frontend

A247630 Number of paths from (0,0) to the line x = n, each segment given by a vector (1,1), (1,-1), or (2,0), not crossing the x-axis, and including no horizontal segment on the x-axis.

n	a(n)
0	1
1	1
2	2
3	4
4	10
5	20
6	50
7	104
8	258
9	552
10	1362
11	2972
12	7306
13	16172
14	39650
15	88720
16	217090
17	489872
18	1196834
19	2719028
20	6634890
21	15157188
22	36949266
23	84799992
24	206549250
25	475894200
26	1158337650
27	2677788492
28	6513914634
29	15102309468
30	36718533570
31	85347160608

[1, 1, 2, 4, 10, 20, 50, 104, 258, 552, 1362, 2972, 7306, 16172, 39650, 88720, 217090, 489872, 1196834, 2719028, 6634890, 15157188, 36949266, 84799992, 206549250, 475894200, 1158337650, 2677788492, 6513914634, 15102309468, 36718533570, 85347160608]

cp's OEIS Frontend

A247630 Number of paths from (0,0) to the line x = n, each segment given by a vector (1,1), (1,-1), or (2,0), not crossing the x-axis, and including no horizontal segment on the x-axis.

Table of values

List of values