A032263 - cp's OEIS frontend

A032263 Number of ways to partition n labeled elements into 4 pie slices allowing the pie to be turned over; number of 2-element proper antichains of an n-element set.

n	a(n)
1	0
2	0
3	0
4	3
5	30
6	195
7	1050
8	5103
9	23310
10	102315
11	437250
12	1834503
13	7597590
14	31175235
15	127067850
16	515396703
17	2083011870
18	8396420955
19	33779000850
20	135696347703
21	544527210150
22	2183335871475
23	8749027724250
24	35043169903503
25	140313869216430
26	561679070838795

[0, 0, 0, 3, 30, 195, 1050, 5103, 23310, 102315, 437250, 1834503, 7597590, 31175235, 127067850, 515396703, 2083011870, 8396420955, 33779000850, 135696347703, 544527210150, 2183335871475, 8749027724250, 35043169903503, 140313869216430, 561679070838795]

cp's OEIS Frontend

A032263 Number of ways to partition n labeled elements into 4 pie slices allowing the pie to be turned over; number of 2-element proper antichains of an n-element set.

Table of values

List of values