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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.

A047949 a(n) is the largest m such that n-m and n+m are both primes, or -1 if no such m exists.

Table of values

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

List of values

[0, 0, 1, 2, 1, 4, 5, 4, 7, 8, 7, 10, 9, 8, 13, 14, 13, 12, 17, 16, 19, 20, 19, 22, 21, 20, 25, 24, 23, 28, 29, 28, 27, 32, 31, 34, 35, 34, 33, 38, 37, 40, 39, 38, 43, 42, 41, 30, 47, 46, 49, 50, 49, 52, 53, 52, 55, 54, 53, 48, 51, 50, 45, 62, 61, 64, 63, 62, 67, 68, 67, 66]

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

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