A169801 - cp's OEIS frontend

A169801 a(n) = ((n-1)^2n^2(n+1)^2)/6 - 2Sum_{l=2..n}Sum_{k=2..n}(n-k+1)(n-l+1)(k-1)(l-1).

n	a(n)
0	0
1	0
2	4
3	64
4	400
5	1600
6	4900
7	12544
8	28224
9	57600
10	108900
11	193600
12	327184
13	529984
14	828100
15	1254400
16	1849600
17	2663424
18	3755844
19	5198400
20	7075600
21	9486400
22	12545764
23	16386304
24	21160000
25	27040000
26	34222500
27	42928704
28	53406864
29	65934400
30	80820100
31	98406400

[0, 0, 4, 64, 400, 1600, 4900, 12544, 28224, 57600, 108900, 193600, 327184, 529984, 828100, 1254400, 1849600, 2663424, 3755844, 5198400, 7075600, 9486400, 12545764, 16386304, 21160000, 27040000, 34222500, 42928704, 53406864, 65934400, 80820100, 98406400]

cp's OEIS Frontend

A169801 a(n) = ((n-1)^2n^2(n+1)^2)/6 - 2Sum_{l=2..n}Sum_{k=2..n}(n-k+1)(n-l+1)(k-1)(l-1).

Table of values

List of values

cp's OEIS Frontend

A169801 a(n) = ((n-1)^2*n^2*(n+1)^2)/6 - 2*Sum_{l=2..n}Sum_{k=2..n}(n-k+1)*(n-l+1)*(k-1)*(l-1).

Table of values

List of values

A169801 a(n) = ((n-1)^2n^2(n+1)^2)/6 - 2Sum_{l=2..n}Sum_{k=2..n}(n-k+1)(n-l+1)(k-1)(l-1).