A255348 - cp's OEIS frontend

A255348 a(1)=1, a(2) = 2; for n > 2, a(n) is the smallest number not already used such that the set of prime divisors of one of the numbers {a(n-1), a(n)} is a subset of the set of prime divisors of the other.

n	a(n)
1	1
2	2
3	4
4	6
5	3
6	9
7	12
8	8
9	10
10	5
11	15
12	25
13	20
14	16
15	14
16	7
17	21
18	27
19	18
20	24
21	30
22	32
23	22
24	11
25	33
26	66
27	36
28	42
29	28
30	49
31	35
32	70
33	40
34	50
35	60
36	45
37	75
38	81
39	39
40	13
41	26
42	52
43	64
44	34
45	17
46	51
47	102
48	48
49	54
50	72
51	78
52	96
53	84
54	56
55	98
56	112
57	126
58	63
59	105
60	125
61	55
62	110
63	44
64	88
65	121
66	77

[1, 2, 4, 6, 3, 9, 12, 8, 10, 5, 15, 25, 20, 16, 14, 7, 21, 27, 18, 24, 30, 32, 22, 11, 33, 66, 36, 42, 28, 49, 35, 70, 40, 50, 60, 45, 75, 81, 39, 13, 26, 52, 64, 34, 17, 51, 102, 48, 54, 72, 78, 96, 84, 56, 98, 112, 126, 63, 105, 125, 55, 110, 44, 88, 121, 77]

cp's OEIS Frontend

A255348 a(1)=1, a(2) = 2; for n > 2, a(n) is the smallest number not already used such that the set of prime divisors of one of the numbers {a(n-1), a(n)} is a subset of the set of prime divisors of the other.

Table of values

List of values

n	a(n)
1	1
2	2
3	4
4	6
5	3
6	9
7	12
8	8
9	10
10	5
11	15
12	25
13	20
14	16
15	14
16	7
17	21
18	27
19	18
20	24
21	30
22	32
23	22
24	11
25	33
26	66
27	36
28	42
29	28
30	49
31	35
32	70
33	40
34	50
35	60
36	45
37	75
38	81
39	39
40	13
41	26
42	52
43	64
44	34
45	17
46	51
47	102
48	48
49	54
50	72
51	78
52	96
53	84
54	56
55	98
56	112
57	126
58	63
59	105
60	125
61	55
62	110
63	44
64	88
65	121
66	77

n	a(n)
1	1
2	2
3	4
4	6
5	3
6	9
7	12
8	8
9	10
10	5
11	15
12	25
13	20
14	16
15	14
16	7
17	21
18	27
19	18
20	24
21	30
22	32
23	22
24	11
25	33
26	66
27	36
28	42
29	28
30	49
31	35
32	70
33	40
34	50
35	60
36	45
37	75
38	81
39	39
40	13
41	26
42	52
43	64
44	34
45	17
46	51
47	102
48	48
49	54
50	72
51	78
52	96
53	84
54	56
55	98
56	112
57	126
58	63
59	105
60	125
61	55
62	110
63	44
64	88
65	121
66	77

n	a(n)
1	1
2	2
3	4
4	6
5	3
6	9
7	12
8	8
9	10
10	5
11	15
12	25
13	20
14	16
15	14
16	7
17	21
18	27
19	18
20	24
21	30
22	32
23	22
24	11
25	33
26	66
27	36
28	42
29	28
30	49
31	35
32	70
33	40
34	50
35	60
36	45
37	75
38	81
39	39
40	13
41	26
42	52
43	64
44	34
45	17
46	51
47	102
48	48
49	54
50	72
51	78
52	96
53	84
54	56
55	98
56	112
57	126
58	63
59	105
60	125
61	55
62	110
63	44
64	88
65	121
66	77