A039655 - cp's OEIS frontend

A039655 Number of iterations of f(x) = sigma(x)-1 applied to n required to reach a prime, or -1 if no prime is ever reached.

n	a(n)
2	0
3	0
4	2
5	0
6	1
7	0
8	2
9	5
10	1
11	0
12	4
13	0
14	1
15	1
16	2
17	0
18	2
19	0
20	1
21	1
22	2
23	0
24	1
25	2
26	1
27	3
28	2
29	0
30	1
31	0
32	5
33	1
34	1
35	1
36	2
37	0
38	1
39	2
40	1
41	0
42	4
43	0
44	1
45	5
46	1
47	0
48	2
49	4
50	2
51	1
52	1
53	0
54	3
55	1
56	3
57	1
58	1
59	0
60	1
61	0
62	4
63	1
64	2
65	1
66	2
67	0
68	3
69	4
70	2
71	0
72	2
73	0
74	1
75	2
76	1
77	4
78	1
79	0
80	2
81	2
82	3
83	0
84	1
85	1
86	1
87	3
88	1
89	0
90	1
91	2
92	1
93	1
94	2
95	3
96	1
97	0
98	3
99	2
100	2
101	0
102	2
103	0
104	2
105	1
106	2

[0, 0, 2, 0, 1, 0, 2, 5, 1, 0, 4, 0, 1, 1, 2, 0, 2, 0, 1, 1, 2, 0, 1, 2, 1, 3, 2, 0, 1, 0, 5, 1, 1, 1, 2, 0, 1, 2, 1, 0, 4, 0, 1, 5, 1, 0, 2, 4, 2, 1, 1, 0, 3, 1, 3, 1, 1, 0, 1, 0, 4, 1, 2, 1, 2, 0, 3, 4, 2, 0, 2, 0, 1, 2, 1, 4, 1, 0, 2, 2, 3, 0, 1, 1, 1, 3, 1, 0, 1, 2, 1, 1, 2, 3, 1, 0, 3, 2, 2, 0, 2, 0, 2, 1, 2]

cp's OEIS Frontend

A039655 Number of iterations of f(x) = sigma(x)-1 applied to n required to reach a prime, or -1 if no prime is ever reached.

Table of values

List of values

n	a(n)
2	0
3	0
4	2
5	0
6	1
7	0
8	2
9	5
10	1
11	0
12	4
13	0
14	1
15	1
16	2
17	0
18	2
19	0
20	1
21	1
22	2
23	0
24	1
25	2
26	1
27	3
28	2
29	0
30	1
31	0
32	5
33	1
34	1
35	1
36	2
37	0
38	1
39	2
40	1
41	0
42	4
43	0
44	1
45	5
46	1
47	0
48	2
49	4
50	2
51	1
52	1
53	0
54	3
55	1
56	3
57	1
58	1
59	0
60	1
61	0
62	4
63	1
64	2
65	1
66	2
67	0
68	3
69	4
70	2
71	0
72	2
73	0
74	1
75	2
76	1
77	4
78	1
79	0
80	2
81	2
82	3
83	0
84	1
85	1
86	1
87	3
88	1
89	0
90	1
91	2
92	1
93	1
94	2
95	3
96	1
97	0
98	3
99	2
100	2
101	0
102	2
103	0
104	2
105	1
106	2

n	a(n)
2	0
3	0
4	2
5	0
6	1
7	0
8	2
9	5
10	1
11	0
12	4
13	0
14	1
15	1
16	2
17	0
18	2
19	0
20	1
21	1
22	2
23	0
24	1
25	2
26	1
27	3
28	2
29	0
30	1
31	0
32	5
33	1
34	1
35	1
36	2
37	0
38	1
39	2
40	1
41	0
42	4
43	0
44	1
45	5
46	1
47	0
48	2
49	4
50	2
51	1
52	1
53	0
54	3
55	1
56	3
57	1
58	1
59	0
60	1
61	0
62	4
63	1
64	2
65	1
66	2
67	0
68	3
69	4
70	2
71	0
72	2
73	0
74	1
75	2
76	1
77	4
78	1
79	0
80	2
81	2
82	3
83	0
84	1
85	1
86	1
87	3
88	1
89	0
90	1
91	2
92	1
93	1
94	2
95	3
96	1
97	0
98	3
99	2
100	2
101	0
102	2
103	0
104	2
105	1
106	2

n	a(n)
2	0
3	0
4	2
5	0
6	1
7	0
8	2
9	5
10	1
11	0
12	4
13	0
14	1
15	1
16	2
17	0
18	2
19	0
20	1
21	1
22	2
23	0
24	1
25	2
26	1
27	3
28	2
29	0
30	1
31	0
32	5
33	1
34	1
35	1
36	2
37	0
38	1
39	2
40	1
41	0
42	4
43	0
44	1
45	5
46	1
47	0
48	2
49	4
50	2
51	1
52	1
53	0
54	3
55	1
56	3
57	1
58	1
59	0
60	1
61	0
62	4
63	1
64	2
65	1
66	2
67	0
68	3
69	4
70	2
71	0
72	2
73	0
74	1
75	2
76	1
77	4
78	1
79	0
80	2
81	2
82	3
83	0
84	1
85	1
86	1
87	3
88	1
89	0
90	1
91	2
92	1
93	1
94	2
95	3
96	1
97	0
98	3
99	2
100	2
101	0
102	2
103	0
104	2
105	1
106	2