A386482 - cp's OEIS frontend

A386482 a(1)=1, a(2)=2; thereafter a(n) is either the greatest number k < a(n-1) not already used such that gcd(k, a(n-1)) > 1, or if no such k exists then a(n) is the smallest number k > a(n-1) not already used such that gcd(k, a(n-1)) > 1.

n	a(n)
1	1
2	2
3	4
4	6
5	3
6	9
7	12
8	10
9	8
10	14
11	7
12	21
13	18
14	16
15	20
16	15
17	5
18	25
19	30
20	28
21	26
22	24
23	22
24	11
25	33
26	27
27	36
28	34
29	32
30	38
31	19
32	57
33	54
34	52
35	50
36	48
37	46
38	44
39	42
40	40
41	35
42	45
43	39
44	13
45	65
46	60
47	58
48	56
49	49
50	63
51	51
52	17
53	68
54	66
55	64
56	62
57	31
58	93
59	90
60	88
61	86
62	84
63	82
64	80
65	78
66	76
67	74
68	72
69	70
70	55
71	75
72	69
73	23
74	92
75	94
76	47
77	141
78	138
79	136
80	134
81	132
82	130
83	128

[1, 2, 4, 6, 3, 9, 12, 10, 8, 14, 7, 21, 18, 16, 20, 15, 5, 25, 30, 28, 26, 24, 22, 11, 33, 27, 36, 34, 32, 38, 19, 57, 54, 52, 50, 48, 46, 44, 42, 40, 35, 45, 39, 13, 65, 60, 58, 56, 49, 63, 51, 17, 68, 66, 64, 62, 31, 93, 90, 88, 86, 84, 82, 80, 78, 76, 74, 72, 70, 55, 75, 69, 23, 92, 94, 47, 141, 138, 136, 134, 132, 130, 128]

cp's OEIS Frontend

A386482 a(1)=1, a(2)=2; thereafter a(n) is either the greatest number k < a(n-1) not already used such that gcd(k, a(n-1)) > 1, or if no such k exists then a(n) is the smallest number k > a(n-1) not already used such that gcd(k, a(n-1)) > 1.

Table of values

List of values

n	a(n)
1	1
2	2
3	4
4	6
5	3
6	9
7	12
8	10
9	8
10	14
11	7
12	21
13	18
14	16
15	20
16	15
17	5
18	25
19	30
20	28
21	26
22	24
23	22
24	11
25	33
26	27
27	36
28	34
29	32
30	38
31	19
32	57
33	54
34	52
35	50
36	48
37	46
38	44
39	42
40	40
41	35
42	45
43	39
44	13
45	65
46	60
47	58
48	56
49	49
50	63
51	51
52	17
53	68
54	66
55	64
56	62
57	31
58	93
59	90
60	88
61	86
62	84
63	82
64	80
65	78
66	76
67	74
68	72
69	70
70	55
71	75
72	69
73	23
74	92
75	94
76	47
77	141
78	138
79	136
80	134
81	132
82	130
83	128

n	a(n)
1	1
2	2
3	4
4	6
5	3
6	9
7	12
8	10
9	8
10	14
11	7
12	21
13	18
14	16
15	20
16	15
17	5
18	25
19	30
20	28
21	26
22	24
23	22
24	11
25	33
26	27
27	36
28	34
29	32
30	38
31	19
32	57
33	54
34	52
35	50
36	48
37	46
38	44
39	42
40	40
41	35
42	45
43	39
44	13
45	65
46	60
47	58
48	56
49	49
50	63
51	51
52	17
53	68
54	66
55	64
56	62
57	31
58	93
59	90
60	88
61	86
62	84
63	82
64	80
65	78
66	76
67	74
68	72
69	70
70	55
71	75
72	69
73	23
74	92
75	94
76	47
77	141
78	138
79	136
80	134
81	132
82	130
83	128

n	a(n)
1	1
2	2
3	4
4	6
5	3
6	9
7	12
8	10
9	8
10	14
11	7
12	21
13	18
14	16
15	20
16	15
17	5
18	25
19	30
20	28
21	26
22	24
23	22
24	11
25	33
26	27
27	36
28	34
29	32
30	38
31	19
32	57
33	54
34	52
35	50
36	48
37	46
38	44
39	42
40	40
41	35
42	45
43	39
44	13
45	65
46	60
47	58
48	56
49	49
50	63
51	51
52	17
53	68
54	66
55	64
56	62
57	31
58	93
59	90
60	88
61	86
62	84
63	82
64	80
65	78
66	76
67	74
68	72
69	70
70	55
71	75
72	69
73	23
74	92
75	94
76	47
77	141
78	138
79	136
80	134
81	132
82	130
83	128