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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.

A089881 Number of primes <= n that are members of twin prime pairs.

Table of values

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

List of values

[0, 0, 0, 0, 2, 2, 3, 3, 3, 3, 3, 3, 5, 5, 5, 5, 5, 5, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15]

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