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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.

A133826 Triangle whose rows are sequences of increasing and decreasing tetrahedral numbers: 1; 1,4,1; 1,4,10,4,1; ... .

Table of values

n a(n)
0 1
1 1
2 4
3 1
4 1
5 4
6 10
7 4
8 1
9 1
10 4
11 10
12 20
13 10
14 4
15 1
16 1
17 4
18 10
19 20
20 35
21 20
22 10
23 4
24 1
25 1
26 4
27 10
28 20
29 35
30 56
31 35
32 20
33 10
34 4
35 1
36 1
37 4
38 10
39 20
40 35
41 56
42 84
43 56
44 35
45 20
46 10
47 4
48 1
49 1
50 4
51 10
52 20
53 35
54 56
55 84
56 120
57 84
58 56
59 35
60 20
61 10
62 4
63 1
64 1
65 4
66 10
67 20
68 35
69 56
70 84
71 120
72 165
73 120
74 84
75 56
76 35
77 20
78 10
79 4
80 1

List of values

[1, 1, 4, 1, 1, 4, 10, 4, 1, 1, 4, 10, 20, 10, 4, 1, 1, 4, 10, 20, 35, 20, 10, 4, 1, 1, 4, 10, 20, 35, 56, 35, 20, 10, 4, 1, 1, 4, 10, 20, 35, 56, 84, 56, 35, 20, 10, 4, 1, 1, 4, 10, 20, 35, 56, 84, 120, 84, 56, 35, 20, 10, 4, 1, 1, 4, 10, 20, 35, 56, 84, 120, 165, 120, 84, 56, 35, 20, 10, 4, 1]

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