A319030 - cp's OEIS frontend

A319030 Triangle read by rows: T(n,k) is the number of permutations pi of [n] such that pi has k+1 valleys and s(pi) avoids the patterns 132 and 321, where s is West's stack-sorting map (0 <= k <= floor((n-1)/2)).

n	a(n)
1	1
2	2
3	4
4	2
5	8
6	14
7	16
8	64
9	8
10	32
11	240
12	92
13	64
14	800
15	624
16	34
17	128
18	2464
19	3248
20	534
21	256
22	7168
23	14336
24	4736
25	144
26	512
27	19968
28	56448
29	31200
30	2852
31	1024
32	53760
33	204288
34	169920
35	31120
36	604
37	2048
38	140800
39	692736
40	808896
41	247280
42	14412

[1, 2, 4, 2, 8, 14, 16, 64, 8, 32, 240, 92, 64, 800, 624, 34, 128, 2464, 3248, 534, 256, 7168, 14336, 4736, 144, 512, 19968, 56448, 31200, 2852, 1024, 53760, 204288, 169920, 31120, 604, 2048, 140800, 692736, 808896, 247280, 14412]

cp's OEIS Frontend

A319030 Triangle read by rows: T(n,k) is the number of permutations pi of [n] such that pi has k+1 valleys and s(pi) avoids the patterns 132 and 321, where s is West's stack-sorting map (0 <= k <= floor((n-1)/2)).

Table of values

List of values