A383777 - cp's OEIS frontend

A383777 a(n) is the number of steps that n requires to reach 0 under the map: x -> 2*x + 1 if x is even; 0 if x = 1; x - lpf(x) otherwise where lpf(x) is the least prime factor of x. a(n) = -1 if 0 is never reached.

n	a(n)
0	0
1	1
2	2
3	1
4	4
5	1
6	2
7	1
8	2
9	3
10	4
11	1
12	4
13	1
14	2
15	5
16	4
17	1
18	2
19	1
20	2
21	3
22	10
23	1
24	10
25	3
26	2
27	11
28	4
29	1
30	2
31	1
32	10
33	3
34	12
35	3
36	2
37	1
38	6
39	3
40	4
41	1
42	8
43	1
44	2
45	9
46	4
47	1
48	2
49	9
50	2
51	3
52	6
53	1
54	2
55	3
56	2
57	3
58	4
59	1
60	8
61	1
62	4
63	9
64	10
65	9
66	10
67	1
68	2
69	11
70	4
71	1
72	4
73	1
74	2
75	5
76	10
77	5
78	2
79	1
80	6
81	3
82	6
83	1

[0, 1, 2, 1, 4, 1, 2, 1, 2, 3, 4, 1, 4, 1, 2, 5, 4, 1, 2, 1, 2, 3, 10, 1, 10, 3, 2, 11, 4, 1, 2, 1, 10, 3, 12, 3, 2, 1, 6, 3, 4, 1, 8, 1, 2, 9, 4, 1, 2, 9, 2, 3, 6, 1, 2, 3, 2, 3, 4, 1, 8, 1, 4, 9, 10, 9, 10, 1, 2, 11, 4, 1, 4, 1, 2, 5, 10, 5, 2, 1, 6, 3, 6, 1]

cp's OEIS Frontend

A383777 a(n) is the number of steps that n requires to reach 0 under the map: x -> 2*x + 1 if x is even; 0 if x = 1; x - lpf(x) otherwise where lpf(x) is the least prime factor of x. a(n) = -1 if 0 is never reached.

Table of values

List of values

n	a(n)
0	0
1	1
2	2
3	1
4	4
5	1
6	2
7	1
8	2
9	3
10	4
11	1
12	4
13	1
14	2
15	5
16	4
17	1
18	2
19	1
20	2
21	3
22	10
23	1
24	10
25	3
26	2
27	11
28	4
29	1
30	2
31	1
32	10
33	3
34	12
35	3
36	2
37	1
38	6
39	3
40	4
41	1
42	8
43	1
44	2
45	9
46	4
47	1
48	2
49	9
50	2
51	3
52	6
53	1
54	2
55	3
56	2
57	3
58	4
59	1
60	8
61	1
62	4
63	9
64	10
65	9
66	10
67	1
68	2
69	11
70	4
71	1
72	4
73	1
74	2
75	5
76	10
77	5
78	2
79	1
80	6
81	3
82	6
83	1

n	a(n)
0	0
1	1
2	2
3	1
4	4
5	1
6	2
7	1
8	2
9	3
10	4
11	1
12	4
13	1
14	2
15	5
16	4
17	1
18	2
19	1
20	2
21	3
22	10
23	1
24	10
25	3
26	2
27	11
28	4
29	1
30	2
31	1
32	10
33	3
34	12
35	3
36	2
37	1
38	6
39	3
40	4
41	1
42	8
43	1
44	2
45	9
46	4
47	1
48	2
49	9
50	2
51	3
52	6
53	1
54	2
55	3
56	2
57	3
58	4
59	1
60	8
61	1
62	4
63	9
64	10
65	9
66	10
67	1
68	2
69	11
70	4
71	1
72	4
73	1
74	2
75	5
76	10
77	5
78	2
79	1
80	6
81	3
82	6
83	1

n	a(n)
0	0
1	1
2	2
3	1
4	4
5	1
6	2
7	1
8	2
9	3
10	4
11	1
12	4
13	1
14	2
15	5
16	4
17	1
18	2
19	1
20	2
21	3
22	10
23	1
24	10
25	3
26	2
27	11
28	4
29	1
30	2
31	1
32	10
33	3
34	12
35	3
36	2
37	1
38	6
39	3
40	4
41	1
42	8
43	1
44	2
45	9
46	4
47	1
48	2
49	9
50	2
51	3
52	6
53	1
54	2
55	3
56	2
57	3
58	4
59	1
60	8
61	1
62	4
63	9
64	10
65	9
66	10
67	1
68	2
69	11
70	4
71	1
72	4
73	1
74	2
75	5
76	10
77	5
78	2
79	1
80	6
81	3
82	6
83	1