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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.

A242012 a(n) is the number of positive integers k <= n for which gpf(k^2 + 1) = gpf(n^2 + 1), where gpf is the greatest prime divisor.

Table of values

n a(n)
1 1
2 1
3 2
4 1
5 1
6 1
7 3
8 2
9 1
10 1
11 1
12 1
13 2
14 1
15 1
16 1
17 2
18 3
19 1
20 1
21 3
22 1
23 1
24 1
25 1
26 1
27 1
28 1
29 1
30 2
31 2
32 2
33 1
34 1
35 1
36 1
37 1
38 4
39 1
40 1
41 3
42 1
43 3
44 1
45 1
46 2
47 5
48 1
49 1
50 2
51 1
52 1
53 1
54 1
55 2
56 1
57 4
58 1
59 1
60 1
61 1
62 1
63 1
64 1
65 1
66 1
67 1
68 4
69 1
70 4
71 1
72 3
73 3
74 1
75 2
76 2
77 1
78 1
79 1
80 1
81 1
82 1
83 3
84 1
85 1
86 1
87 1

List of values

[1, 1, 2, 1, 1, 1, 3, 2, 1, 1, 1, 1, 2, 1, 1, 1, 2, 3, 1, 1, 3, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 1, 1, 1, 1, 1, 4, 1, 1, 3, 1, 3, 1, 1, 2, 5, 1, 1, 2, 1, 1, 1, 1, 2, 1, 4, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 4, 1, 4, 1, 3, 3, 1, 2, 2, 1, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1]