A121216 - cp's OEIS frontend

A121216 a(1)=1, a(2) = 2; thereafter a(n) = the smallest positive integer which does not occur earlier in the sequence and which is coprime to a(n-2).

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

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

cp's OEIS Frontend

A121216 a(1)=1, a(2) = 2; thereafter a(n) = the smallest positive integer which does not occur earlier in the sequence and which is coprime to a(n-2).

Table of values

List of values

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

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

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