A289997 - cp's OEIS frontend

A289997 Numbers n whose trajectory under iteration of the map k -> (sigma(k)+phi(k))/2 never reaches a fraction (that is, either the trajectory reaches a prime, which is a fixed point, or diverges to infinity).

n	a(n)
1	1
2	2
3	3
4	5
5	6
6	7
7	10
8	11
9	13
10	17
11	19
12	21
13	22
14	23
15	26
16	27
17	29
18	30
19	31
20	37
21	38
22	39
23	40
24	41
25	43
26	44
27	45
28	46
29	47
30	51
31	52
32	53
33	57
34	58
35	59
36	60
37	61
38	65
39	66
40	67
41	68
42	71
43	73
44	74
45	75
46	79
47	80
48	82
49	83
50	89
51	91
52	92
53	97
54	101
55	103
56	106
57	107
58	109
59	113
60	114
61	115
62	116
63	117
64	126
65	127
66	131
67	133
68	134
69	135
70	136
71	137

[1, 2, 3, 5, 6, 7, 10, 11, 13, 17, 19, 21, 22, 23, 26, 27, 29, 30, 31, 37, 38, 39, 40, 41, 43, 44, 45, 46, 47, 51, 52, 53, 57, 58, 59, 60, 61, 65, 66, 67, 68, 71, 73, 74, 75, 79, 80, 82, 83, 89, 91, 92, 97, 101, 103, 106, 107, 109, 113, 114, 115, 116, 117, 126, 127, 131, 133, 134, 135, 136, 137]

cp's OEIS Frontend

A289997 Numbers n whose trajectory under iteration of the map k -> (sigma(k)+phi(k))/2 never reaches a fraction (that is, either the trajectory reaches a prime, which is a fixed point, or diverges to infinity).

Table of values

List of values

n	a(n)
1	1
2	2
3	3
4	5
5	6
6	7
7	10
8	11
9	13
10	17
11	19
12	21
13	22
14	23
15	26
16	27
17	29
18	30
19	31
20	37
21	38
22	39
23	40
24	41
25	43
26	44
27	45
28	46
29	47
30	51
31	52
32	53
33	57
34	58
35	59
36	60
37	61
38	65
39	66
40	67
41	68
42	71
43	73
44	74
45	75
46	79
47	80
48	82
49	83
50	89
51	91
52	92
53	97
54	101
55	103
56	106
57	107
58	109
59	113
60	114
61	115
62	116
63	117
64	126
65	127
66	131
67	133
68	134
69	135
70	136
71	137

n	a(n)
1	1
2	2
3	3
4	5
5	6
6	7
7	10
8	11
9	13
10	17
11	19
12	21
13	22
14	23
15	26
16	27
17	29
18	30
19	31
20	37
21	38
22	39
23	40
24	41
25	43
26	44
27	45
28	46
29	47
30	51
31	52
32	53
33	57
34	58
35	59
36	60
37	61
38	65
39	66
40	67
41	68
42	71
43	73
44	74
45	75
46	79
47	80
48	82
49	83
50	89
51	91
52	92
53	97
54	101
55	103
56	106
57	107
58	109
59	113
60	114
61	115
62	116
63	117
64	126
65	127
66	131
67	133
68	134
69	135
70	136
71	137

n	a(n)
1	1
2	2
3	3
4	5
5	6
6	7
7	10
8	11
9	13
10	17
11	19
12	21
13	22
14	23
15	26
16	27
17	29
18	30
19	31
20	37
21	38
22	39
23	40
24	41
25	43
26	44
27	45
28	46
29	47
30	51
31	52
32	53
33	57
34	58
35	59
36	60
37	61
38	65
39	66
40	67
41	68
42	71
43	73
44	74
45	75
46	79
47	80
48	82
49	83
50	89
51	91
52	92
53	97
54	101
55	103
56	106
57	107
58	109
59	113
60	114
61	115
62	116
63	117
64	126
65	127
66	131
67	133
68	134
69	135
70	136
71	137