A145876 - cp's OEIS frontend

A145876 Triangle read by rows: T(n,k) is the number of permutations of [n] having k-1 alternating descents (1<=k<=n). The index i is an alternating descent of a permutation p if either i is odd and p(i)>p(i+1), or i is even and p(i)

n	a(n)
1	1
2	1
3	1
4	2
5	2
6	2
7	5
8	7
9	7
10	5
11	16
12	26
13	36
14	26
15	16
16	61
17	117
18	182
19	182
20	117
21	61
22	272
23	594
24	1056
25	1196
26	1056
27	594
28	272
29	1385
30	3407
31	6669
32	8699
33	8699
34	6669
35	3407
36	1385
37	7936
38	21682
39	46348
40	67054
41	76840
42	67054
43	46348
44	21682
45	7936
46	50521
47	151853
48	350240
49	556952
50	704834
51	704834
52	556952
53	350240
54	151853
55	50521

[1, 1, 1, 2, 2, 2, 5, 7, 7, 5, 16, 26, 36, 26, 16, 61, 117, 182, 182, 117, 61, 272, 594, 1056, 1196, 1056, 594, 272, 1385, 3407, 6669, 8699, 8699, 6669, 3407, 1385, 7936, 21682, 46348, 67054, 76840, 67054, 46348, 21682, 7936, 50521, 151853, 350240, 556952, 704834, 704834, 556952, 350240, 151853, 50521]

cp's OEIS Frontend

A145876 Triangle read by rows: T(n,k) is the number of permutations of [n] having k-1 alternating descents (1<=k<=n). The index i is an alternating descent of a permutation p if either i is odd and p(i)>p(i+1), or i is even and p(i)

Table of values

List of values