A354753 - cp's OEIS frontend

A354753 a(1) = 1, a(2) = 2; for n > 2, a(n) is the smallest positive number that shares a factor with a(n-1) and the product a(n) * a(n-1) is distinct from all previous products a(i) * a(i-1), i=2..n-1.

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

[1, 2, 2, 4, 4, 6, 2, 10, 4, 8, 6, 3, 3, 9, 6, 6, 10, 5, 5, 15, 3, 21, 6, 12, 8, 8, 10, 10, 12, 9, 9, 15, 6, 14, 2, 22, 4, 14, 7, 7, 21, 9, 18, 8, 14, 10, 15, 12, 14, 14, 16, 8, 20, 10, 22, 6, 26, 2, 34, 4, 26, 8, 22, 11, 11, 33, 3, 39, 6, 32, 8, 30, 9, 24, 12, 21, 14, 20, 15, 15, 21, 18, 18]

cp's OEIS Frontend

A354753 a(1) = 1, a(2) = 2; for n > 2, a(n) is the smallest positive number that shares a factor with a(n-1) and the product a(n) * a(n-1) is distinct from all previous products a(i) * a(i-1), i=2..n-1.

Table of values

List of values

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

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

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