A267830 - cp's OEIS frontend

A267830 Number of nonprime numbers in {n, f(n), f(f(n)), ...., 1}, where f is the Collatz function defined by f(x) = x/2 if x is even; f(x) = 3x + 1 if x is odd.

n	a(n)
1	1
2	1
3	5
4	2
5	4
6	6
7	11
8	3
9	14
10	5
11	10
12	7
13	7
14	12
15	14
16	4
17	9
18	15
19	14
20	6
21	7
22	11
23	12
24	8
25	17
26	8
27	87
28	13
29	13
30	15
31	83
32	5
33	20
34	10
35	11
36	16
37	15
38	15
39	24
40	7
41	85
42	8
43	22
44	12
45	13
46	13
47	82
48	9
49	18
50	18
51	19
52	9
53	9
54	88
55	89
56	14
57	25
58	14
59	22
60	16
61	15
62	84
63	88
64	6
65	21
66	21
67	19
68	11
69	12
70	12
71	81

[1, 1, 5, 2, 4, 6, 11, 3, 14, 5, 10, 7, 7, 12, 14, 4, 9, 15, 14, 6, 7, 11, 12, 8, 17, 8, 87, 13, 13, 15, 83, 5, 20, 10, 11, 16, 15, 15, 24, 7, 85, 8, 22, 12, 13, 13, 82, 9, 18, 18, 19, 9, 9, 88, 89, 14, 25, 14, 22, 16, 15, 84, 88, 6, 21, 21, 19, 11, 12, 12, 81]

cp's OEIS Frontend

A267830 Number of nonprime numbers in {n, f(n), f(f(n)), ...., 1}, where f is the Collatz function defined by f(x) = x/2 if x is even; f(x) = 3x + 1 if x is odd.

Table of values

List of values

n	a(n)
1	1
2	1
3	5
4	2
5	4
6	6
7	11
8	3
9	14
10	5
11	10
12	7
13	7
14	12
15	14
16	4
17	9
18	15
19	14
20	6
21	7
22	11
23	12
24	8
25	17
26	8
27	87
28	13
29	13
30	15
31	83
32	5
33	20
34	10
35	11
36	16
37	15
38	15
39	24
40	7
41	85
42	8
43	22
44	12
45	13
46	13
47	82
48	9
49	18
50	18
51	19
52	9
53	9
54	88
55	89
56	14
57	25
58	14
59	22
60	16
61	15
62	84
63	88
64	6
65	21
66	21
67	19
68	11
69	12
70	12
71	81

n	a(n)
1	1
2	1
3	5
4	2
5	4
6	6
7	11
8	3
9	14
10	5
11	10
12	7
13	7
14	12
15	14
16	4
17	9
18	15
19	14
20	6
21	7
22	11
23	12
24	8
25	17
26	8
27	87
28	13
29	13
30	15
31	83
32	5
33	20
34	10
35	11
36	16
37	15
38	15
39	24
40	7
41	85
42	8
43	22
44	12
45	13
46	13
47	82
48	9
49	18
50	18
51	19
52	9
53	9
54	88
55	89
56	14
57	25
58	14
59	22
60	16
61	15
62	84
63	88
64	6
65	21
66	21
67	19
68	11
69	12
70	12
71	81

n	a(n)
1	1
2	1
3	5
4	2
5	4
6	6
7	11
8	3
9	14
10	5
11	10
12	7
13	7
14	12
15	14
16	4
17	9
18	15
19	14
20	6
21	7
22	11
23	12
24	8
25	17
26	8
27	87
28	13
29	13
30	15
31	83
32	5
33	20
34	10
35	11
36	16
37	15
38	15
39	24
40	7
41	85
42	8
43	22
44	12
45	13
46	13
47	82
48	9
49	18
50	18
51	19
52	9
53	9
54	88
55	89
56	14
57	25
58	14
59	22
60	16
61	15
62	84
63	88
64	6
65	21
66	21
67	19
68	11
69	12
70	12
71	81