A385613 - cp's OEIS frontend

A385613 Number of steps that n requires to reach 0 under the map: x-> x^2 - 1 if x is an odd prime, floor(x/3) if x is even, otherwise x - 1. a(n) = -1 if 0 is never reached.

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

[0, 1, 1, 3, 2, 4, 2, 7, 2, 3, 4, 9, 3, 6, 3, 4, 5, 8, 3, 10, 3, 4, 8, 14, 3, 4, 3, 4, 4, 10, 5, 15, 5, 6, 10, 11, 4, 10, 4, 5, 7, 8, 4, 14, 4, 5, 5, 10, 6, 7, 6, 7, 9, 15, 4, 5, 4, 5, 11, 9, 4, 18, 4, 5, 5, 6, 9, 10, 9, 10, 15, 9, 4, 22, 4, 5, 5, 6, 4, 11, 4]

cp's OEIS Frontend

A385613 Number of steps that n requires to reach 0 under the map: x-> x^2 - 1 if x is an odd prime, floor(x/3) if x is even, otherwise x - 1. a(n) = -1 if 0 is never reached.

Table of values

List of values

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

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

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