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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.

A289508 a(n) is the GCD of the indices j for which the j-th prime p_j divides n.

Table of values

n a(n)
1 0
2 1
3 2
4 1
5 3
6 1
7 4
8 1
9 2
10 1
11 5
12 1
13 6
14 1
15 1
16 1
17 7
18 1
19 8
20 1
21 2
22 1
23 9
24 1
25 3
26 1
27 2
28 1
29 10
30 1
31 11
32 1
33 1
34 1
35 1
36 1
37 12
38 1
39 2
40 1
41 13
42 1
43 14
44 1
45 1
46 1
47 15
48 1
49 4
50 1
51 1
52 1
53 16
54 1
55 1
56 1
57 2
58 1
59 17
60 1
61 18
62 1
63 2
64 1
65 3
66 1
67 19
68 1
69 1
70 1
71 20
72 1
73 21
74 1
75 1
76 1
77 1
78 1
79 22
80 1
81 2
82 1
83 23

List of values

[0, 1, 2, 1, 3, 1, 4, 1, 2, 1, 5, 1, 6, 1, 1, 1, 7, 1, 8, 1, 2, 1, 9, 1, 3, 1, 2, 1, 10, 1, 11, 1, 1, 1, 1, 1, 12, 1, 2, 1, 13, 1, 14, 1, 1, 1, 15, 1, 4, 1, 1, 1, 16, 1, 1, 1, 2, 1, 17, 1, 18, 1, 2, 1, 3, 1, 19, 1, 1, 1, 20, 1, 21, 1, 1, 1, 1, 1, 22, 1, 2, 1, 23]