A152891 - cp's OEIS frontend

A152891 a(1) = b(1) = 0; for n > 1, b(n) = b(n-1) + n-1 + a(n-1) and a(n) = a(n-1) + n-1 + b(n).

n	a(n)
1	0
2	2
3	9
4	29
5	83
6	226
7	602
8	1588
9	4171
10	10935
11	28645
12	75012
13	196404
14	514214
15	1346253
16	3524561
17	9227447
18	24157798
19	63245966
20	165580120
21	433494415
22	1134903147
23	2971215049
24	7778742024
25	20365011048
26	53316291146
27	139583862417

[0, 2, 9, 29, 83, 226, 602, 1588, 4171, 10935, 28645, 75012, 196404, 514214, 1346253, 3524561, 9227447, 24157798, 63245966, 165580120, 433494415, 1134903147, 2971215049, 7778742024, 20365011048, 53316291146, 139583862417]

cp's OEIS Frontend

A152891 a(1) = b(1) = 0; for n > 1, b(n) = b(n-1) + n-1 + a(n-1) and a(n) = a(n-1) + n-1 + b(n).

Table of values

List of values