A078893 - cp's OEIS frontend

A078893 Composite numbers k such that phi(k) - 1 is prime, where phi is Euler's totient function (A000010).

n	a(n)
1	8
2	9
3	10
4	12
5	14
6	15
7	16
8	18
9	20
10	21
11	24
12	25
13	26
14	27
15	28
16	30
17	33
18	35
19	36
20	38
21	39
22	42
23	44
24	45
25	49
26	50
27	51
28	52
29	54
30	56
31	62
32	64
33	65
34	66
35	68
36	69
37	70
38	72
39	77
40	78
41	80
42	81
43	84
44	86
45	90
46	91
47	92
48	93
49	95
50	96
51	98
52	99
53	102
54	104
55	105
56	111
57	112
58	117
59	120
60	121
61	122
62	123
63	124
64	129
65	130
66	133

[8, 9, 10, 12, 14, 15, 16, 18, 20, 21, 24, 25, 26, 27, 28, 30, 33, 35, 36, 38, 39, 42, 44, 45, 49, 50, 51, 52, 54, 56, 62, 64, 65, 66, 68, 69, 70, 72, 77, 78, 80, 81, 84, 86, 90, 91, 92, 93, 95, 96, 98, 99, 102, 104, 105, 111, 112, 117, 120, 121, 122, 123, 124, 129, 130, 133]

cp's OEIS Frontend

A078893 Composite numbers k such that phi(k) - 1 is prime, where phi is Euler's totient function (A000010).

Table of values

List of values

n	a(n)
1	8
2	9
3	10
4	12
5	14
6	15
7	16
8	18
9	20
10	21
11	24
12	25
13	26
14	27
15	28
16	30
17	33
18	35
19	36
20	38
21	39
22	42
23	44
24	45
25	49
26	50
27	51
28	52
29	54
30	56
31	62
32	64
33	65
34	66
35	68
36	69
37	70
38	72
39	77
40	78
41	80
42	81
43	84
44	86
45	90
46	91
47	92
48	93
49	95
50	96
51	98
52	99
53	102
54	104
55	105
56	111
57	112
58	117
59	120
60	121
61	122
62	123
63	124
64	129
65	130
66	133

n	a(n)
1	8
2	9
3	10
4	12
5	14
6	15
7	16
8	18
9	20
10	21
11	24
12	25
13	26
14	27
15	28
16	30
17	33
18	35
19	36
20	38
21	39
22	42
23	44
24	45
25	49
26	50
27	51
28	52
29	54
30	56
31	62
32	64
33	65
34	66
35	68
36	69
37	70
38	72
39	77
40	78
41	80
42	81
43	84
44	86
45	90
46	91
47	92
48	93
49	95
50	96
51	98
52	99
53	102
54	104
55	105
56	111
57	112
58	117
59	120
60	121
61	122
62	123
63	124
64	129
65	130
66	133

n	a(n)
1	8
2	9
3	10
4	12
5	14
6	15
7	16
8	18
9	20
10	21
11	24
12	25
13	26
14	27
15	28
16	30
17	33
18	35
19	36
20	38
21	39
22	42
23	44
24	45
25	49
26	50
27	51
28	52
29	54
30	56
31	62
32	64
33	65
34	66
35	68
36	69
37	70
38	72
39	77
40	78
41	80
42	81
43	84
44	86
45	90
46	91
47	92
48	93
49	95
50	96
51	98
52	99
53	102
54	104
55	105
56	111
57	112
58	117
59	120
60	121
61	122
62	123
63	124
64	129
65	130
66	133