A374404 - cp's OEIS frontend

A374404 a(1) = 1, a(2) = 2. Let i = a(n-2), j = a(n-1). For n > 2 if rad(ij) is primorial number A002110(t), a(n) is least novel k such that rad(ijk) = A002110(t+1). Otherwise, if rad(ij) is not primorial, a(n) is least novel k such that rad(ijk) = A002110(s), where prime(s) = A006530(i*j); rad = A007947.

n	a(n)
1	1
2	2
3	3
4	5
5	4
6	6
7	10
8	7
9	9
10	20
11	14
12	12
13	15
14	21
15	8
16	25
17	18
18	28
19	30
20	11
21	35
22	24
23	22
24	70
25	27
26	33
27	140
28	13
29	66
30	105
31	26
32	44
33	210
34	39
35	55
36	42
37	52
38	110
39	63
40	65
41	88
42	84
43	40
44	77
45	36
46	45
47	49
48	16
49	60
50	56
51	99
52	50
53	98
54	48
55	75
56	112
57	121
58	90
59	126
60	132
61	80
62	147
63	143
64	100
65	168

[1, 2, 3, 5, 4, 6, 10, 7, 9, 20, 14, 12, 15, 21, 8, 25, 18, 28, 30, 11, 35, 24, 22, 70, 27, 33, 140, 13, 66, 105, 26, 44, 210, 39, 55, 42, 52, 110, 63, 65, 88, 84, 40, 77, 36, 45, 49, 16, 60, 56, 99, 50, 98, 48, 75, 112, 121, 90, 126, 132, 80, 147, 143, 100, 168]

cp's OEIS Frontend

Table of values

List of values

n	a(n)
1	1
2	2
3	3
4	5
5	4
6	6
7	10
8	7
9	9
10	20
11	14
12	12
13	15
14	21
15	8
16	25
17	18
18	28
19	30
20	11
21	35
22	24
23	22
24	70
25	27
26	33
27	140
28	13
29	66
30	105
31	26
32	44
33	210
34	39
35	55
36	42
37	52
38	110
39	63
40	65
41	88
42	84
43	40
44	77
45	36
46	45
47	49
48	16
49	60
50	56
51	99
52	50
53	98
54	48
55	75
56	112
57	121
58	90
59	126
60	132
61	80
62	147
63	143
64	100
65	168

n	a(n)
1	1
2	2
3	3
4	5
5	4
6	6
7	10
8	7
9	9
10	20
11	14
12	12
13	15
14	21
15	8
16	25
17	18
18	28
19	30
20	11
21	35
22	24
23	22
24	70
25	27
26	33
27	140
28	13
29	66
30	105
31	26
32	44
33	210
34	39
35	55
36	42
37	52
38	110
39	63
40	65
41	88
42	84
43	40
44	77
45	36
46	45
47	49
48	16
49	60
50	56
51	99
52	50
53	98
54	48
55	75
56	112
57	121
58	90
59	126
60	132
61	80
62	147
63	143
64	100
65	168

n	a(n)
1	1
2	2
3	3
4	5
5	4
6	6
7	10
8	7
9	9
10	20
11	14
12	12
13	15
14	21
15	8
16	25
17	18
18	28
19	30
20	11
21	35
22	24
23	22
24	70
25	27
26	33
27	140
28	13
29	66
30	105
31	26
32	44
33	210
34	39
35	55
36	42
37	52
38	110
39	63
40	65
41	88
42	84
43	40
44	77
45	36
46	45
47	49
48	16
49	60
50	56
51	99
52	50
53	98
54	48
55	75
56	112
57	121
58	90
59	126
60	132
61	80
62	147
63	143
64	100
65	168