A270139 - cp's OEIS frontend

A270139 a(n)=n when n<=3, otherwise a(n) is the smallest unused positive integer which is not coprime to the two previous terms.

n	a(n)
1	1
2	2
3	3
4	6
5	9
6	12
7	15
8	10
9	5
10	20
11	25
12	30
13	35
14	14
15	7
16	21
17	28
18	18
19	4
20	8
21	16
22	22
23	24
24	26
25	32
26	34
27	36
28	38
29	40
30	42
31	44
32	33
33	11
34	55
35	66
36	45
37	27
38	39
39	48
40	51
41	54
42	57
43	60
44	63
45	56
46	49
47	70
48	77
49	84
50	88
51	46
52	50
53	52
54	58
55	62
56	64
57	68
58	72
59	74
60	76
61	78
62	80
63	65
64	75
65	85
66	90
67	95
68	100
69	105
70	96

[1, 2, 3, 6, 9, 12, 15, 10, 5, 20, 25, 30, 35, 14, 7, 21, 28, 18, 4, 8, 16, 22, 24, 26, 32, 34, 36, 38, 40, 42, 44, 33, 11, 55, 66, 45, 27, 39, 48, 51, 54, 57, 60, 63, 56, 49, 70, 77, 84, 88, 46, 50, 52, 58, 62, 64, 68, 72, 74, 76, 78, 80, 65, 75, 85, 90, 95, 100, 105, 96]

cp's OEIS Frontend

A270139 a(n)=n when n<=3, otherwise a(n) is the smallest unused positive integer which is not coprime to the two previous terms.

Table of values

List of values

n	a(n)
1	1
2	2
3	3
4	6
5	9
6	12
7	15
8	10
9	5
10	20
11	25
12	30
13	35
14	14
15	7
16	21
17	28
18	18
19	4
20	8
21	16
22	22
23	24
24	26
25	32
26	34
27	36
28	38
29	40
30	42
31	44
32	33
33	11
34	55
35	66
36	45
37	27
38	39
39	48
40	51
41	54
42	57
43	60
44	63
45	56
46	49
47	70
48	77
49	84
50	88
51	46
52	50
53	52
54	58
55	62
56	64
57	68
58	72
59	74
60	76
61	78
62	80
63	65
64	75
65	85
66	90
67	95
68	100
69	105
70	96

n	a(n)
1	1
2	2
3	3
4	6
5	9
6	12
7	15
8	10
9	5
10	20
11	25
12	30
13	35
14	14
15	7
16	21
17	28
18	18
19	4
20	8
21	16
22	22
23	24
24	26
25	32
26	34
27	36
28	38
29	40
30	42
31	44
32	33
33	11
34	55
35	66
36	45
37	27
38	39
39	48
40	51
41	54
42	57
43	60
44	63
45	56
46	49
47	70
48	77
49	84
50	88
51	46
52	50
53	52
54	58
55	62
56	64
57	68
58	72
59	74
60	76
61	78
62	80
63	65
64	75
65	85
66	90
67	95
68	100
69	105
70	96

n	a(n)
1	1
2	2
3	3
4	6
5	9
6	12
7	15
8	10
9	5
10	20
11	25
12	30
13	35
14	14
15	7
16	21
17	28
18	18
19	4
20	8
21	16
22	22
23	24
24	26
25	32
26	34
27	36
28	38
29	40
30	42
31	44
32	33
33	11
34	55
35	66
36	45
37	27
38	39
39	48
40	51
41	54
42	57
43	60
44	63
45	56
46	49
47	70
48	77
49	84
50	88
51	46
52	50
53	52
54	58
55	62
56	64
57	68
58	72
59	74
60	76
61	78
62	80
63	65
64	75
65	85
66	90
67	95
68	100
69	105
70	96