A047162 - cp's OEIS frontend

A047162 Number of nonempty subsets of {1,2,...,n} in which exactly 2/3 of the elements are <= n/2.

n	a(n)
1	0
2	0
3	0
4	2
5	3
6	9
7	12
8	30
9	40
10	100
11	135
12	335
13	455
14	1127
15	1540
16	3822
17	5250
18	13050
19	18000
20	44802
21	62007
22	154517
23	214467
24	534963
25	744315
26	1858155
27	2590679
28	6472167
29	9039823
30	22597759
31	31612324
32	79067374
33	110761494
34	277164294
35	388742706
36	973184312
37	1366460867
38	3422117189

[0, 0, 0, 2, 3, 9, 12, 30, 40, 100, 135, 335, 455, 1127, 1540, 3822, 5250, 13050, 18000, 44802, 62007, 154517, 214467, 534963, 744315, 1858155, 2590679, 6472167, 9039823, 22597759, 31612324, 79067374, 110761494, 277164294, 388742706, 973184312, 1366460867, 3422117189]

cp's OEIS Frontend

A047162 Number of nonempty subsets of {1,2,...,n} in which exactly 2/3 of the elements are <= n/2.

Table of values

List of values