A287666 - cp's OEIS frontend

A287666 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-3 is member of a block >= b-1.

n	a(n)
0	1
1	1
2	2
3	5
4	15
5	52
6	202
7	861
8	3970
9	19596
10	102703
11	567867
12	3295439
13	19986462
14	126231946
15	827759525
16	5621051650
17	39439867696
18	285368007479
19	2125566382124
20	16273261632111
21	127881070062521
22	1030221084660031
23	8498826714433335
24	71721238761675612
25	618573094313147709

[1, 1, 2, 5, 15, 52, 202, 861, 3970, 19596, 102703, 567867, 3295439, 19986462, 126231946, 827759525, 5621051650, 39439867696, 285368007479, 2125566382124, 16273261632111, 127881070062521, 1030221084660031, 8498826714433335, 71721238761675612, 618573094313147709]

cp's OEIS Frontend

A287666 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-3 is member of a block >= b-1.

Table of values

List of values