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This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A138159 Triangle read by rows: T(n,k) is the number of permutations of [n] having k occurrences of the pattern 321 (n>=1, 0<=k<=n(n-1)(n-2)/6).

Table of values

n a(n)
0 1
1 1
2 2
3 5
4 1
5 14
6 6
7 3
8 0
9 1
10 42
11 27
12 24
13 7
14 9
15 6
16 0
17 4
18 0
19 0
20 1
21 132
22 110
23 133
24 70
25 74
26 54
27 37
28 32
29 24
30 12
31 16
32 6
33 6
34 8
35 0
36 0
37 5
38 0
39 0
40 0
41 1
42 429
43 429
44 635
45 461
46 507
47 395
48 387
49 320
50 260
51 232
52 191
53 162
54 104
55 130
56 100
57 24
58 74
59 62
60 18
61 32
62 10
63 30
64 13
65 8
66 0
67 10
68 10
69 0
70 0
71 0
72 6
73 0
74 0
75 0
76 0
77 1

List of values

[1, 1, 2, 5, 1, 14, 6, 3, 0, 1, 42, 27, 24, 7, 9, 6, 0, 4, 0, 0, 1, 132, 110, 133, 70, 74, 54, 37, 32, 24, 12, 16, 6, 6, 8, 0, 0, 5, 0, 0, 0, 1, 429, 429, 635, 461, 507, 395, 387, 320, 260, 232, 191, 162, 104, 130, 100, 24, 74, 62, 18, 32, 10, 30, 13, 8, 0, 10, 10, 0, 0, 0, 6, 0, 0, 0, 0, 1]