A247623 - cp's OEIS frontend

A247623 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	9
5	19
6	44
7	96
8	225
9	501
10	1182
11	2668
12	6321
13	14407
14	34232
15	78592
16	187137
17	432073
18	1030490
19	2390004
20	5707449
21	13286043
22	31760676
23	74160672
24	177435297
25	415382397
26	994551222
27	2333445468
28	5590402785
29	13141557519
30	31500824304
31	74174404608
32	177880832001

[1, 1, 2, 4, 9, 19, 44, 96, 225, 501, 1182, 2668, 6321, 14407, 34232, 78592, 187137, 432073, 1030490, 2390004, 5707449, 13286043, 31760676, 74160672, 177435297, 415382397, 994551222, 2333445468, 5590402785, 13141557519, 31500824304, 74174404608, 177880832001]

cp's OEIS Frontend

A247623 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