A379165 - cp's OEIS frontend

A379165 a(1) = 1, a(2) = 2; for n > 2, a(n) is the smallest unused positive number that is either coprime to both a(n-1) and a(n-2) or shares a factor with both a(n-1) and a(n-2).

n	a(n)
1	1
2	2
3	3
4	5
5	4
6	7
7	9
8	8
9	6
10	10
11	11
12	13
13	12
14	17
15	19
16	14
17	15
18	18
19	20
20	16
21	21
22	23
23	22
24	25
25	27
26	26
27	24
28	28
29	29
30	31
31	30
32	37
33	41
34	32
35	33
36	35
37	34
38	39
39	36
40	42
41	38
42	40
43	43
44	47
45	44
46	45
47	48
48	49
49	53
50	46
51	51
52	54
53	55
54	50
55	57
56	59
57	52
58	61
59	63
60	58
61	56
62	60
63	62
64	64
65	65
66	67
67	66
68	71
69	73
70	68
71	69
72	72
73	75
74	70
75	78
76	74
77	76
78	77
79	79
80	80
81	81
82	83
83	82
84	85
85	87
86	86
87	84
88	88
89	89
90	91

[1, 2, 3, 5, 4, 7, 9, 8, 6, 10, 11, 13, 12, 17, 19, 14, 15, 18, 20, 16, 21, 23, 22, 25, 27, 26, 24, 28, 29, 31, 30, 37, 41, 32, 33, 35, 34, 39, 36, 42, 38, 40, 43, 47, 44, 45, 48, 49, 53, 46, 51, 54, 55, 50, 57, 59, 52, 61, 63, 58, 56, 60, 62, 64, 65, 67, 66, 71, 73, 68, 69, 72, 75, 70, 78, 74, 76, 77, 79, 80, 81, 83, 82, 85, 87, 86, 84, 88, 89, 91]

cp's OEIS Frontend

A379165 a(1) = 1, a(2) = 2; for n > 2, a(n) is the smallest unused positive number that is either coprime to both a(n-1) and a(n-2) or shares a factor with both a(n-1) and a(n-2).

Table of values

List of values

n	a(n)
1	1
2	2
3	3
4	5
5	4
6	7
7	9
8	8
9	6
10	10
11	11
12	13
13	12
14	17
15	19
16	14
17	15
18	18
19	20
20	16
21	21
22	23
23	22
24	25
25	27
26	26
27	24
28	28
29	29
30	31
31	30
32	37
33	41
34	32
35	33
36	35
37	34
38	39
39	36
40	42
41	38
42	40
43	43
44	47
45	44
46	45
47	48
48	49
49	53
50	46
51	51
52	54
53	55
54	50
55	57
56	59
57	52
58	61
59	63
60	58
61	56
62	60
63	62
64	64
65	65
66	67
67	66
68	71
69	73
70	68
71	69
72	72
73	75
74	70
75	78
76	74
77	76
78	77
79	79
80	80
81	81
82	83
83	82
84	85
85	87
86	86
87	84
88	88
89	89
90	91

n	a(n)
1	1
2	2
3	3
4	5
5	4
6	7
7	9
8	8
9	6
10	10
11	11
12	13
13	12
14	17
15	19
16	14
17	15
18	18
19	20
20	16
21	21
22	23
23	22
24	25
25	27
26	26
27	24
28	28
29	29
30	31
31	30
32	37
33	41
34	32
35	33
36	35
37	34
38	39
39	36
40	42
41	38
42	40
43	43
44	47
45	44
46	45
47	48
48	49
49	53
50	46
51	51
52	54
53	55
54	50
55	57
56	59
57	52
58	61
59	63
60	58
61	56
62	60
63	62
64	64
65	65
66	67
67	66
68	71
69	73
70	68
71	69
72	72
73	75
74	70
75	78
76	74
77	76
78	77
79	79
80	80
81	81
82	83
83	82
84	85
85	87
86	86
87	84
88	88
89	89
90	91

n	a(n)
1	1
2	2
3	3
4	5
5	4
6	7
7	9
8	8
9	6
10	10
11	11
12	13
13	12
14	17
15	19
16	14
17	15
18	18
19	20
20	16
21	21
22	23
23	22
24	25
25	27
26	26
27	24
28	28
29	29
30	31
31	30
32	37
33	41
34	32
35	33
36	35
37	34
38	39
39	36
40	42
41	38
42	40
43	43
44	47
45	44
46	45
47	48
48	49
49	53
50	46
51	51
52	54
53	55
54	50
55	57
56	59
57	52
58	61
59	63
60	58
61	56
62	60
63	62
64	64
65	65
66	67
67	66
68	71
69	73
70	68
71	69
72	72
73	75
74	70
75	78
76	74
77	76
78	77
79	79
80	80
81	81
82	83
83	82
84	85
85	87
86	86
87	84
88	88
89	89
90	91