A291785 - cp's OEIS frontend

A291785 Iterate the map A291784: k -> (psi(k)+phi(k))/2, starting with n, until a power of a prime (A000961) is reached, or -1 if that never happens.

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

[1, 2, 3, 4, 5, 7, 7, 8, 9, 11, 11, 16, 13, 16, 16, 16, 17, 23, 19, 23, 23, 23, 23, 47, 25, 27, 27, 47, 29, 47, 31, 32, 83, 83, 83, 83, 37, 47, 47, 47, 41, 83, 43, 47, -1, 47, 47, -1, 49, -1, 83, 83, 53, 83, -1, -1, 59, 59, 59, -1, 61, 83, 83, 64, 83, 83, 67, -1, -1, -1, 71, -1, 73]

cp's OEIS Frontend

A291785 Iterate the map A291784: k -> (psi(k)+phi(k))/2, starting with n, until a power of a prime (A000961) is reached, or -1 if that never happens.

Table of values

List of values

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

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

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