A130810 - cp's OEIS frontend

A130810 If X_1,...,X_n is a partition of a 2n-set X into 2-blocks then a(n) is equal to the number of 4-subsets of X containing none of X_i, (i=1,...,n).

n	a(n)
4	16
5	80
6	240
7	560
8	1120
9	2016
10	3360
11	5280
12	7920
13	11440
14	16016
15	21840
16	29120
17	38080
18	48960
19	62016
20	77520
21	95760
22	117040
23	141680
24	170016
25	202400
26	239200
27	280800
28	327600
29	380016
30	438480
31	503440
32	575360
33	654720
34	742016
35	837760
36	942480
37	1056720

[16, 80, 240, 560, 1120, 2016, 3360, 5280, 7920, 11440, 16016, 21840, 29120, 38080, 48960, 62016, 77520, 95760, 117040, 141680, 170016, 202400, 239200, 280800, 327600, 380016, 438480, 503440, 575360, 654720, 742016, 837760, 942480, 1056720]

cp's OEIS Frontend

A130810 If X_1,...,X_n is a partition of a 2n-set X into 2-blocks then a(n) is equal to the number of 4-subsets of X containing none of X_i, (i=1,...,n).

Table of values

List of values