A290633 - cp's OEIS frontend

A290633 Lexicographically earliest sequence of positive integers such that, for any m and n > 0, gcd(a(n), a(n+1)) > 1 and a(n) != a(n+2), and if m < n then a(m) != a(n) or a(m+1) != a(n+1).

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

[2, 2, 4, 4, 2, 6, 3, 3, 6, 2, 8, 4, 6, 6, 4, 8, 2, 10, 4, 12, 2, 14, 4, 10, 2, 12, 3, 9, 6, 8, 8, 6, 9, 3, 12, 4, 14, 2, 16, 4, 18, 2, 20, 4, 16, 2, 18, 3, 15, 5, 5, 10, 6, 12, 8, 10, 5, 15, 3, 18, 4, 20, 2, 22, 4, 24, 2, 26, 4, 22, 2, 24, 3, 21, 6, 10, 8, 12]

cp's OEIS Frontend

A290633 Lexicographically earliest sequence of positive integers such that, for any m and n > 0, gcd(a(n), a(n+1)) > 1 and a(n) != a(n+2), and if m < n then a(m) != a(n) or a(m+1) != a(n+1).

Table of values

List of values

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

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

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