A374645 - cp's OEIS frontend

A374645 a(1) = 1, a(2) = 6, a(3) = 2; for n > 3, a(n) is the smallest unused positive number that is coprime to a(n-1) but has a common factor with any other previous term that has a common factor with a(n-1).

n	a(n)
1	1
2	6
3	2
4	3
5	4
6	9
7	8
8	15
9	14
10	27
11	5
12	12
13	7
14	10
15	21
16	16
17	25
18	18
19	35
20	22
21	39
22	20
23	11
24	24
25	13
26	30
27	49
28	26
29	33
30	28
31	45
32	32
33	51
34	38
35	55
36	34
37	19
38	36
39	17
40	40
41	57
42	44
43	63
44	46
45	65
46	42
47	23
48	48
49	77
50	50
51	69
52	52
53	75
54	56
55	81
56	58
57	85
58	54
59	29
60	60
61	91
62	62
63	87
64	64
65	31
66	66
67	95
68	68
69	93
70	70
71	99
72	74
73	105
74	76
75	37

[1, 6, 2, 3, 4, 9, 8, 15, 14, 27, 5, 12, 7, 10, 21, 16, 25, 18, 35, 22, 39, 20, 11, 24, 13, 30, 49, 26, 33, 28, 45, 32, 51, 38, 55, 34, 19, 36, 17, 40, 57, 44, 63, 46, 65, 42, 23, 48, 77, 50, 69, 52, 75, 56, 81, 58, 85, 54, 29, 60, 91, 62, 87, 64, 31, 66, 95, 68, 93, 70, 99, 74, 105, 76, 37]

cp's OEIS Frontend

A374645 a(1) = 1, a(2) = 6, a(3) = 2; for n > 3, a(n) is the smallest unused positive number that is coprime to a(n-1) but has a common factor with any other previous term that has a common factor with a(n-1).

Table of values

List of values

n	a(n)
1	1
2	6
3	2
4	3
5	4
6	9
7	8
8	15
9	14
10	27
11	5
12	12
13	7
14	10
15	21
16	16
17	25
18	18
19	35
20	22
21	39
22	20
23	11
24	24
25	13
26	30
27	49
28	26
29	33
30	28
31	45
32	32
33	51
34	38
35	55
36	34
37	19
38	36
39	17
40	40
41	57
42	44
43	63
44	46
45	65
46	42
47	23
48	48
49	77
50	50
51	69
52	52
53	75
54	56
55	81
56	58
57	85
58	54
59	29
60	60
61	91
62	62
63	87
64	64
65	31
66	66
67	95
68	68
69	93
70	70
71	99
72	74
73	105
74	76
75	37

n	a(n)
1	1
2	6
3	2
4	3
5	4
6	9
7	8
8	15
9	14
10	27
11	5
12	12
13	7
14	10
15	21
16	16
17	25
18	18
19	35
20	22
21	39
22	20
23	11
24	24
25	13
26	30
27	49
28	26
29	33
30	28
31	45
32	32
33	51
34	38
35	55
36	34
37	19
38	36
39	17
40	40
41	57
42	44
43	63
44	46
45	65
46	42
47	23
48	48
49	77
50	50
51	69
52	52
53	75
54	56
55	81
56	58
57	85
58	54
59	29
60	60
61	91
62	62
63	87
64	64
65	31
66	66
67	95
68	68
69	93
70	70
71	99
72	74
73	105
74	76
75	37

n	a(n)
1	1
2	6
3	2
4	3
5	4
6	9
7	8
8	15
9	14
10	27
11	5
12	12
13	7
14	10
15	21
16	16
17	25
18	18
19	35
20	22
21	39
22	20
23	11
24	24
25	13
26	30
27	49
28	26
29	33
30	28
31	45
32	32
33	51
34	38
35	55
36	34
37	19
38	36
39	17
40	40
41	57
42	44
43	63
44	46
45	65
46	42
47	23
48	48
49	77
50	50
51	69
52	52
53	75
54	56
55	81
56	58
57	85
58	54
59	29
60	60
61	91
62	62
63	87
64	64
65	31
66	66
67	95
68	68
69	93
70	70
71	99
72	74
73	105
74	76
75	37