A275605 - cp's OEIS frontend

A275605 Number of set partitions of [n] such that j is member of block b only if b = 1 or at least one of j-1, j-2 is member of a block >= b-1.

n	a(n)
0	1
1	1
2	2
3	5
4	15
5	51
6	191
7	773
8	3336
9	15207
10	72697
11	362447
12	1876392
13	10051083
14	55544661
15	315899245
16	1845139684
17	11048651523
18	67719859612
19	424287619507
20	2714074517843
21	17706680249505
22	117704101959444
23	796546613501759
24	5483490237025393
25	38372546811580251

[1, 1, 2, 5, 15, 51, 191, 773, 3336, 15207, 72697, 362447, 1876392, 10051083, 55544661, 315899245, 1845139684, 11048651523, 67719859612, 424287619507, 2714074517843, 17706680249505, 117704101959444, 796546613501759, 5483490237025393, 38372546811580251]

cp's OEIS Frontend

A275605 Number of set partitions of [n] such that j is member of block b only if b = 1 or at least one of j-1, j-2 is member of a block >= b-1.

Table of values

List of values