A255582 - cp's OEIS frontend

A255582 a(n)=n when n <= 3, otherwise a(n) is the smallest positive number not yet in the sequence such that gcd(a(n), a(n-1)) <= gcd(a(n), a(n-2)) > 1.

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

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

cp's OEIS Frontend

A255582 a(n)=n when n <= 3, otherwise a(n) is the smallest positive number not yet in the sequence such that gcd(a(n), a(n-1)) <= gcd(a(n), a(n-2)) > 1.

Table of values

List of values

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

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

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