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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.

A107347 Number of even semiprimes strictly between prime(n) and 2*prime(n).

Table of values

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

List of values

[0, 1, 1, 1, 1, 2, 2, 3, 3, 3, 4, 4, 4, 5, 5, 6, 6, 7, 7, 8, 9, 9, 9, 9, 9, 10, 11, 11, 12, 13, 12, 13, 13, 14, 13, 14, 15, 15, 15, 16, 16, 17, 18, 19, 19, 20, 19, 18, 18, 19, 20, 21, 22, 23, 23, 23, 24, 25, 25, 25, 26, 27, 26, 27, 28, 28, 28, 28, 28, 29, 30, 30, 30, 31, 32, 32, 32, 32]

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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