A340420 - cp's OEIS frontend

A340420 The number of steps that n requires to reach 1 under the map: m -> m/2 if m is even, m-> 3*m + 1 if m is an odd prime, otherwise m -> m - 1. a(n) = -1 if 1 is never reached.

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

[0, 1, 7, 2, 5, 8, 16, 3, 4, 6, 14, 9, 9, 17, 18, 4, 12, 5, 20, 7, 8, 15, 16, 10, 11, 10, 11, 18, 18, 19, 19, 5, 6, 13, 14, 6, 21, 21, 22, 8, 22, 9, 9, 16, 17, 17, 17, 11, 12, 12, 13, 11, 11, 12, 13, 19, 20, 19, 32, 20, 20, 20, 21, 6, 7, 7, 27, 14, 15, 15, 15]

cp's OEIS Frontend

A340420 The number of steps that n requires to reach 1 under the map: m -> m/2 if m is even, m-> 3*m + 1 if m is an odd prime, otherwise m -> m - 1. a(n) = -1 if 1 is never reached.

Table of values

List of values

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

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

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