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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.

A366445 Triangle read by rows: T(n,k) = A023900(n/k)*phi(k) if k divides n, T(n,k) = 0 otherwise (n >= 1, 1 <= k <= n).

Table of values

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

List of values

[1, -1, 1, -2, 0, 2, -1, -1, 0, 2, -4, 0, 0, 0, 4, 2, -2, -2, 0, 0, 2, -6, 0, 0, 0, 0, 0, 6, -1, -1, 0, -2, 0, 0, 0, 4, -2, 0, -4, 0, 0, 0, 0, 0, 6, 4, -4, 0, 0, -4, 0, 0, 0, 0, 4, -10, 0, 0, 0, 0, 0, 0, 0, 0, 0, 10, 2, 2, -2, -4, 0, -2, 0, 0, 0, 0, 0, 4]

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