A128564 - cp's OEIS frontend

A128564 Triangle, read by rows, where T(n,k) equals the number of permutations of {1..n+1} with [(nk+k)/2] inversions for n>=k>=0.

n	a(n)
0	1
1	1
2	1
3	1
4	2
5	1
6	1
7	5
8	5
9	1
10	1
11	9
12	22
13	15
14	1
15	1
16	29
17	90
18	90
19	29
20	1
21	1
22	49
23	359
24	573
25	359
26	98
27	1
28	1
29	174
30	1415
31	3450
32	3450
33	1415
34	174
35	1
36	1
37	285
38	5545
39	17957
40	29228
41	21450
42	5545
43	628
44	1
45	1
46	1068
47	21670
48	110010
49	230131
50	230131
51	110010
52	21670
53	1068
54	1

[1, 1, 1, 1, 2, 1, 1, 5, 5, 1, 1, 9, 22, 15, 1, 1, 29, 90, 90, 29, 1, 1, 49, 359, 573, 359, 98, 1, 1, 174, 1415, 3450, 3450, 1415, 174, 1, 1, 285, 5545, 17957, 29228, 21450, 5545, 628, 1, 1, 1068, 21670, 110010, 230131, 230131, 110010, 21670, 1068, 1]

cp's OEIS Frontend

A128564 Triangle, read by rows, where T(n,k) equals the number of permutations of {1..n+1} with [(nk+k)/2] inversions for n>=k>=0.

Table of values

List of values