A252865 - cp's OEIS frontend

A252865 a(n) = n if n <= 3, otherwise the smallest squarefree number not occurring earlier having at least one common factor with a(n-2), but none with a(n-1).

n	a(n)
1	1
2	2
3	3
4	10
5	21
6	5
7	6
8	35
9	22
10	7
11	11
12	14
13	33
14	26
15	15
16	13
17	30
18	91
19	34
20	39
21	17
22	42
23	85
24	38
25	51
26	19
27	66
28	95
29	46
30	55
31	23
32	65
33	69
34	70
35	57
36	58
37	93
38	29
39	31
40	87
41	62
42	105
43	74
44	77
45	37
46	110
47	111
48	82
49	129
50	41
51	43
52	123
53	86
54	141
55	106
56	47
57	53
58	94
59	159
60	118
61	165
62	59
63	78
64	295

[1, 2, 3, 10, 21, 5, 6, 35, 22, 7, 11, 14, 33, 26, 15, 13, 30, 91, 34, 39, 17, 42, 85, 38, 51, 19, 66, 95, 46, 55, 23, 65, 69, 70, 57, 58, 93, 29, 31, 87, 62, 105, 74, 77, 37, 110, 111, 82, 129, 41, 43, 123, 86, 141, 106, 47, 53, 94, 159, 118, 165, 59, 78, 295]

cp's OEIS Frontend

A252865 a(n) = n if n <= 3, otherwise the smallest squarefree number not occurring earlier having at least one common factor with a(n-2), but none with a(n-1).

Table of values

List of values

n	a(n)
1	1
2	2
3	3
4	10
5	21
6	5
7	6
8	35
9	22
10	7
11	11
12	14
13	33
14	26
15	15
16	13
17	30
18	91
19	34
20	39
21	17
22	42
23	85
24	38
25	51
26	19
27	66
28	95
29	46
30	55
31	23
32	65
33	69
34	70
35	57
36	58
37	93
38	29
39	31
40	87
41	62
42	105
43	74
44	77
45	37
46	110
47	111
48	82
49	129
50	41
51	43
52	123
53	86
54	141
55	106
56	47
57	53
58	94
59	159
60	118
61	165
62	59
63	78
64	295

n	a(n)
1	1
2	2
3	3
4	10
5	21
6	5
7	6
8	35
9	22
10	7
11	11
12	14
13	33
14	26
15	15
16	13
17	30
18	91
19	34
20	39
21	17
22	42
23	85
24	38
25	51
26	19
27	66
28	95
29	46
30	55
31	23
32	65
33	69
34	70
35	57
36	58
37	93
38	29
39	31
40	87
41	62
42	105
43	74
44	77
45	37
46	110
47	111
48	82
49	129
50	41
51	43
52	123
53	86
54	141
55	106
56	47
57	53
58	94
59	159
60	118
61	165
62	59
63	78
64	295

n	a(n)
1	1
2	2
3	3
4	10
5	21
6	5
7	6
8	35
9	22
10	7
11	11
12	14
13	33
14	26
15	15
16	13
17	30
18	91
19	34
20	39
21	17
22	42
23	85
24	38
25	51
26	19
27	66
28	95
29	46
30	55
31	23
32	65
33	69
34	70
35	57
36	58
37	93
38	29
39	31
40	87
41	62
42	105
43	74
44	77
45	37
46	110
47	111
48	82
49	129
50	41
51	43
52	123
53	86
54	141
55	106
56	47
57	53
58	94
59	159
60	118
61	165
62	59
63	78
64	295