A128565 - cp's OEIS frontend

A128565 Column 1 of triangle A128564; a(n) equals the number of permutations of {1..n+2} with [n/2+1] inversions for n>=0.

n	a(n)
0	1
1	2
2	5
3	9
4	29
5	49
6	174
7	285
8	1068
9	1717
10	6655
11	10569
12	41926
13	66013
14	266338
15	416687
16	1703027
17	2651355
18	10947079
19	16976806
20	70673825
21	109256095
22	457927079
23	706071989
24	2976282415
25	4579020513
26	19395654894
27	29784426945
28	126688273871
29	194231327451
30	829176461458

[1, 2, 5, 9, 29, 49, 174, 285, 1068, 1717, 6655, 10569, 41926, 66013, 266338, 416687, 1703027, 2651355, 10947079, 16976806, 70673825, 109256095, 457927079, 706071989, 2976282415, 4579020513, 19395654894, 29784426945, 126688273871, 194231327451, 829176461458]

cp's OEIS Frontend

A128565 Column 1 of triangle A128564; a(n) equals the number of permutations of {1..n+2} with [n/2+1] inversions for n>=0.

Table of values

List of values