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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.

A297307 Given n, define the sequence x(1) = n, thereafter if x(i) is even set x(i+1) = x(i)/2, if x(i) is odd and divisible by 3, 5 or 7 set x(i+1) = 5*x(i) + 1, otherwise set x(i+1) = 3*x(i) + 1. Then a(n) is the smallest i>1 such that x(i) = 1, 5, or 553, or -1 if none of those numbers is ever reached.

Table of values

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

List of values

[4, 2, 6, 3, 7, 7, 22, 4, 19, 2, 10, 8, 5, 23, 19, 5, 8, 20, 16, 3, 9, 11, 17, 9, 39, 6, 12, 24, 14, 20, 78, 6, 36, 9, 15, 21, 27, 17, 34, 4, 81, 10, 39, 12, 55, 18, 76, 10, 31, 40, 10, 7, 7, 13, 46, 25, 32, 15, 28, 21, 21, 79, 37, 7, 37, 37, 23, 10, 43, 16, 74, 22]

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