A323356 - cp's OEIS frontend

A323356 For a rational number p/q let f(p/q) = (p+q) / (A000120(p) + A000120(q)); a(n) is obtained by iterating f, starting at n/1, until an integer is reached (and then a(n) = that integer), or if no integer is ever reached then a(n) = -1.

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

[1, 2, 2, 2, 2, 2, 2, -1, 7, -1, 3, 7, 7, -1, 7, -1, 6, -1, 5, 7, 7, -1, -1, -1, -1, 8, -1, -1, 6, 8, -1, 8, 11, 8, 9, 8, -1, 8, 8, 11, -1, 11, 11, 11, -1, 11, 8, -1, 8, 11, -1, -1, 11, 11, 8, 16, -1, 15, 10, 16, -1, -1, 15, 14, 22, 14, 17, 23, 11, 15, 11, 11, 8, 12, 11, 11, 16, 12, 11]

cp's OEIS Frontend

A323356 For a rational number p/q let f(p/q) = (p+q) / (A000120(p) + A000120(q)); a(n) is obtained by iterating f, starting at n/1, until an integer is reached (and then a(n) = that integer), or if no integer is ever reached then a(n) = -1.

Table of values

List of values

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

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

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