A084820 - cp's OEIS frontend

A084820 Numbers n such that n, sigma(n) and phi(n) form an integer triangle, where sigma=A000203 is the divisor sum and phi=A000010 the totient.

n	a(n)
1	1
2	3
3	5
4	7
5	9
6	11
7	13
8	17
9	19
10	21
11	23
12	25
13	27
14	29
15	31
16	33
17	35
18	37
19	39
20	41
21	43
22	47
23	49
24	51
25	53
26	55
27	57
28	59
29	61
30	65
31	67
32	69
33	71
34	73
35	77
36	79
37	81
38	83
39	85
40	87
41	89
42	91
43	93
44	95
45	97
46	99
47	101
48	103
49	107
50	109
51	111
52	113
53	115
54	117
55	119
56	121
57	123
58	125
59	127
60	129
61	131
62	133
63	137

[1, 3, 5, 7, 9, 11, 13, 17, 19, 21, 23, 25, 27, 29, 31, 33, 35, 37, 39, 41, 43, 47, 49, 51, 53, 55, 57, 59, 61, 65, 67, 69, 71, 73, 77, 79, 81, 83, 85, 87, 89, 91, 93, 95, 97, 99, 101, 103, 107, 109, 111, 113, 115, 117, 119, 121, 123, 125, 127, 129, 131, 133, 137]

cp's OEIS Frontend

A084820 Numbers n such that n, sigma(n) and phi(n) form an integer triangle, where sigma=A000203 is the divisor sum and phi=A000010 the totient.

Table of values

List of values

n	a(n)
1	1
2	3
3	5
4	7
5	9
6	11
7	13
8	17
9	19
10	21
11	23
12	25
13	27
14	29
15	31
16	33
17	35
18	37
19	39
20	41
21	43
22	47
23	49
24	51
25	53
26	55
27	57
28	59
29	61
30	65
31	67
32	69
33	71
34	73
35	77
36	79
37	81
38	83
39	85
40	87
41	89
42	91
43	93
44	95
45	97
46	99
47	101
48	103
49	107
50	109
51	111
52	113
53	115
54	117
55	119
56	121
57	123
58	125
59	127
60	129
61	131
62	133
63	137

n	a(n)
1	1
2	3
3	5
4	7
5	9
6	11
7	13
8	17
9	19
10	21
11	23
12	25
13	27
14	29
15	31
16	33
17	35
18	37
19	39
20	41
21	43
22	47
23	49
24	51
25	53
26	55
27	57
28	59
29	61
30	65
31	67
32	69
33	71
34	73
35	77
36	79
37	81
38	83
39	85
40	87
41	89
42	91
43	93
44	95
45	97
46	99
47	101
48	103
49	107
50	109
51	111
52	113
53	115
54	117
55	119
56	121
57	123
58	125
59	127
60	129
61	131
62	133
63	137

n	a(n)
1	1
2	3
3	5
4	7
5	9
6	11
7	13
8	17
9	19
10	21
11	23
12	25
13	27
14	29
15	31
16	33
17	35
18	37
19	39
20	41
21	43
22	47
23	49
24	51
25	53
26	55
27	57
28	59
29	61
30	65
31	67
32	69
33	71
34	73
35	77
36	79
37	81
38	83
39	85
40	87
41	89
42	91
43	93
44	95
45	97
46	99
47	101
48	103
49	107
50	109
51	111
52	113
53	115
54	117
55	119
56	121
57	123
58	125
59	127
60	129
61	131
62	133
63	137