A358176 - cp's OEIS frontend

A358176 a(1) = 1, a(2) = 2; for n > 2, a(n) is the smallest positive number not occurring earlier that shares a factor with sigma(a(n-1)).

n	a(n)
1	1
2	2
3	3
4	4
5	7
6	6
7	8
8	5
9	9
10	13
11	10
12	12
13	14
14	15
15	16
16	31
17	18
18	21
19	20
20	22
21	24
22	25
23	62
24	26
25	27
26	28
27	30
28	32
29	33
30	34
31	36
32	35
33	38
34	39
35	40
36	42
37	44
38	45
39	46
40	48
41	50
42	51
43	52
44	49
45	19
46	54
47	55
48	56
49	57
50	58
51	60
52	63
53	64
54	127
55	66
56	68
57	69
58	70
59	72
60	65
61	74
62	75
63	76
64	77
65	78
66	80
67	81
68	11
69	82
70	84
71	86
72	87
73	85
74	88
75	90
76	91
77	92

[1, 2, 3, 4, 7, 6, 8, 5, 9, 13, 10, 12, 14, 15, 16, 31, 18, 21, 20, 22, 24, 25, 62, 26, 27, 28, 30, 32, 33, 34, 36, 35, 38, 39, 40, 42, 44, 45, 46, 48, 50, 51, 52, 49, 19, 54, 55, 56, 57, 58, 60, 63, 64, 127, 66, 68, 69, 70, 72, 65, 74, 75, 76, 77, 78, 80, 81, 11, 82, 84, 86, 87, 85, 88, 90, 91, 92]

cp's OEIS Frontend

A358176 a(1) = 1, a(2) = 2; for n > 2, a(n) is the smallest positive number not occurring earlier that shares a factor with sigma(a(n-1)).

Table of values

List of values

n	a(n)
1	1
2	2
3	3
4	4
5	7
6	6
7	8
8	5
9	9
10	13
11	10
12	12
13	14
14	15
15	16
16	31
17	18
18	21
19	20
20	22
21	24
22	25
23	62
24	26
25	27
26	28
27	30
28	32
29	33
30	34
31	36
32	35
33	38
34	39
35	40
36	42
37	44
38	45
39	46
40	48
41	50
42	51
43	52
44	49
45	19
46	54
47	55
48	56
49	57
50	58
51	60
52	63
53	64
54	127
55	66
56	68
57	69
58	70
59	72
60	65
61	74
62	75
63	76
64	77
65	78
66	80
67	81
68	11
69	82
70	84
71	86
72	87
73	85
74	88
75	90
76	91
77	92

n	a(n)
1	1
2	2
3	3
4	4
5	7
6	6
7	8
8	5
9	9
10	13
11	10
12	12
13	14
14	15
15	16
16	31
17	18
18	21
19	20
20	22
21	24
22	25
23	62
24	26
25	27
26	28
27	30
28	32
29	33
30	34
31	36
32	35
33	38
34	39
35	40
36	42
37	44
38	45
39	46
40	48
41	50
42	51
43	52
44	49
45	19
46	54
47	55
48	56
49	57
50	58
51	60
52	63
53	64
54	127
55	66
56	68
57	69
58	70
59	72
60	65
61	74
62	75
63	76
64	77
65	78
66	80
67	81
68	11
69	82
70	84
71	86
72	87
73	85
74	88
75	90
76	91
77	92

n	a(n)
1	1
2	2
3	3
4	4
5	7
6	6
7	8
8	5
9	9
10	13
11	10
12	12
13	14
14	15
15	16
16	31
17	18
18	21
19	20
20	22
21	24
22	25
23	62
24	26
25	27
26	28
27	30
28	32
29	33
30	34
31	36
32	35
33	38
34	39
35	40
36	42
37	44
38	45
39	46
40	48
41	50
42	51
43	52
44	49
45	19
46	54
47	55
48	56
49	57
50	58
51	60
52	63
53	64
54	127
55	66
56	68
57	69
58	70
59	72
60	65
61	74
62	75
63	76
64	77
65	78
66	80
67	81
68	11
69	82
70	84
71	86
72	87
73	85
74	88
75	90
76	91
77	92