A375281 - cp's OEIS frontend

A375281 Lexicographically earliest infinite sequence of distinct positive integers such that for all n > 1 a(n-1), a(n) do not have the same number of distinct prime divisors, whereas the squarefree kernel of their product is a primorial number.

n	a(n)
1	1
2	2
3	6
4	3
5	10
6	9
7	12
8	4
9	15
10	8
11	18
12	5
13	24
14	16
15	30
16	7
17	60
18	14
19	90
20	20
21	27
22	36
23	25
24	42
25	35
26	66
27	175
28	84
29	40
30	81
31	48
32	32
33	45
34	64
35	54
36	70
37	21
38	110
39	63
40	120
41	28
42	105
43	22
44	210
45	11
46	420
47	33
48	140
49	72
50	125
51	96
52	128
53	75
54	126
55	50
56	150
57	49
58	180
59	56
60	165
61	98
62	240
63	77
64	270

[1, 2, 6, 3, 10, 9, 12, 4, 15, 8, 18, 5, 24, 16, 30, 7, 60, 14, 90, 20, 27, 36, 25, 42, 35, 66, 175, 84, 40, 81, 48, 32, 45, 64, 54, 70, 21, 110, 63, 120, 28, 105, 22, 210, 11, 420, 33, 140, 72, 125, 96, 128, 75, 126, 50, 150, 49, 180, 56, 165, 98, 240, 77, 270]

cp's OEIS Frontend

A375281 Lexicographically earliest infinite sequence of distinct positive integers such that for all n > 1 a(n-1), a(n) do not have the same number of distinct prime divisors, whereas the squarefree kernel of their product is a primorial number.

Table of values

List of values

n	a(n)
1	1
2	2
3	6
4	3
5	10
6	9
7	12
8	4
9	15
10	8
11	18
12	5
13	24
14	16
15	30
16	7
17	60
18	14
19	90
20	20
21	27
22	36
23	25
24	42
25	35
26	66
27	175
28	84
29	40
30	81
31	48
32	32
33	45
34	64
35	54
36	70
37	21
38	110
39	63
40	120
41	28
42	105
43	22
44	210
45	11
46	420
47	33
48	140
49	72
50	125
51	96
52	128
53	75
54	126
55	50
56	150
57	49
58	180
59	56
60	165
61	98
62	240
63	77
64	270

n	a(n)
1	1
2	2
3	6
4	3
5	10
6	9
7	12
8	4
9	15
10	8
11	18
12	5
13	24
14	16
15	30
16	7
17	60
18	14
19	90
20	20
21	27
22	36
23	25
24	42
25	35
26	66
27	175
28	84
29	40
30	81
31	48
32	32
33	45
34	64
35	54
36	70
37	21
38	110
39	63
40	120
41	28
42	105
43	22
44	210
45	11
46	420
47	33
48	140
49	72
50	125
51	96
52	128
53	75
54	126
55	50
56	150
57	49
58	180
59	56
60	165
61	98
62	240
63	77
64	270

n	a(n)
1	1
2	2
3	6
4	3
5	10
6	9
7	12
8	4
9	15
10	8
11	18
12	5
13	24
14	16
15	30
16	7
17	60
18	14
19	90
20	20
21	27
22	36
23	25
24	42
25	35
26	66
27	175
28	84
29	40
30	81
31	48
32	32
33	45
34	64
35	54
36	70
37	21
38	110
39	63
40	120
41	28
42	105
43	22
44	210
45	11
46	420
47	33
48	140
49	72
50	125
51	96
52	128
53	75
54	126
55	50
56	150
57	49
58	180
59	56
60	165
61	98
62	240
63	77
64	270