A354225 - cp's OEIS frontend

A354225 Lexicographically earliest sequence of distinct positive integers such that a(1) = 1 and for any n > 1, n / gcd(n, a(n)) and a(n) / gcd(n, a(n)) are prime.

n	a(n)
1	1
2	3
3	2
4	6
5	7
6	4
7	5
8	12
9	15
10	14
11	13
12	8
13	11
14	10
15	9
16	24
17	19
18	27
19	17
20	28
21	33
22	26
23	29
24	16
25	35
26	22
27	18
28	20
29	23
30	42
31	37
32	48
33	21
34	38
35	25
36	54
37	31
38	34
39	51
40	56
41	43
42	30
43	41
44	52
45	63
46	58
47	53
48	32
49	77
50	70
51	39
52	44
53	47
54	36
55	65
56	40
57	69
58	46
59	61
60	84
61	59
62	74
63	45
64	96
65	55
66	78
67	71

[1, 3, 2, 6, 7, 4, 5, 12, 15, 14, 13, 8, 11, 10, 9, 24, 19, 27, 17, 28, 33, 26, 29, 16, 35, 22, 18, 20, 23, 42, 37, 48, 21, 38, 25, 54, 31, 34, 51, 56, 43, 30, 41, 52, 63, 58, 53, 32, 77, 70, 39, 44, 47, 36, 65, 40, 69, 46, 61, 84, 59, 74, 45, 96, 55, 78, 71]

cp's OEIS Frontend

A354225 Lexicographically earliest sequence of distinct positive integers such that a(1) = 1 and for any n > 1, n / gcd(n, a(n)) and a(n) / gcd(n, a(n)) are prime.

Table of values

List of values

n	a(n)
1	1
2	3
3	2
4	6
5	7
6	4
7	5
8	12
9	15
10	14
11	13
12	8
13	11
14	10
15	9
16	24
17	19
18	27
19	17
20	28
21	33
22	26
23	29
24	16
25	35
26	22
27	18
28	20
29	23
30	42
31	37
32	48
33	21
34	38
35	25
36	54
37	31
38	34
39	51
40	56
41	43
42	30
43	41
44	52
45	63
46	58
47	53
48	32
49	77
50	70
51	39
52	44
53	47
54	36
55	65
56	40
57	69
58	46
59	61
60	84
61	59
62	74
63	45
64	96
65	55
66	78
67	71

n	a(n)
1	1
2	3
3	2
4	6
5	7
6	4
7	5
8	12
9	15
10	14
11	13
12	8
13	11
14	10
15	9
16	24
17	19
18	27
19	17
20	28
21	33
22	26
23	29
24	16
25	35
26	22
27	18
28	20
29	23
30	42
31	37
32	48
33	21
34	38
35	25
36	54
37	31
38	34
39	51
40	56
41	43
42	30
43	41
44	52
45	63
46	58
47	53
48	32
49	77
50	70
51	39
52	44
53	47
54	36
55	65
56	40
57	69
58	46
59	61
60	84
61	59
62	74
63	45
64	96
65	55
66	78
67	71

n	a(n)
1	1
2	3
3	2
4	6
5	7
6	4
7	5
8	12
9	15
10	14
11	13
12	8
13	11
14	10
15	9
16	24
17	19
18	27
19	17
20	28
21	33
22	26
23	29
24	16
25	35
26	22
27	18
28	20
29	23
30	42
31	37
32	48
33	21
34	38
35	25
36	54
37	31
38	34
39	51
40	56
41	43
42	30
43	41
44	52
45	63
46	58
47	53
48	32
49	77
50	70
51	39
52	44
53	47
54	36
55	65
56	40
57	69
58	46
59	61
60	84
61	59
62	74
63	45
64	96
65	55
66	78
67	71