A128556 - cp's OEIS frontend

A128556 a(1)=1. a(n) = the smallest positive multiple of d(a(n-1)) that does not occur earlier in the sequence, where d(m) is the number of positive divisors of m.

n	a(n)
1	1
2	2
3	4
4	3
5	6
6	8
7	12
8	18
9	24
10	16
11	5
12	10
13	20
14	30
15	32
16	36
17	9
18	15
19	28
20	42
21	40
22	48
23	50
24	54
25	56
26	64
27	7
28	14
29	44
30	60
31	72
32	84
33	96
34	108
35	120
36	80
37	70
38	88
39	104
40	112
41	90
42	132
43	144
44	45
45	66
46	128
47	136
48	152
49	160
50	156
51	168
52	176
53	100
54	27
55	52
56	78
57	184
58	192
59	98
60	102
61	200
62	180

[1, 2, 4, 3, 6, 8, 12, 18, 24, 16, 5, 10, 20, 30, 32, 36, 9, 15, 28, 42, 40, 48, 50, 54, 56, 64, 7, 14, 44, 60, 72, 84, 96, 108, 120, 80, 70, 88, 104, 112, 90, 132, 144, 45, 66, 128, 136, 152, 160, 156, 168, 176, 100, 27, 52, 78, 184, 192, 98, 102, 200, 180]

cp's OEIS Frontend

A128556 a(1)=1. a(n) = the smallest positive multiple of d(a(n-1)) that does not occur earlier in the sequence, where d(m) is the number of positive divisors of m.

Table of values

List of values

n	a(n)
1	1
2	2
3	4
4	3
5	6
6	8
7	12
8	18
9	24
10	16
11	5
12	10
13	20
14	30
15	32
16	36
17	9
18	15
19	28
20	42
21	40
22	48
23	50
24	54
25	56
26	64
27	7
28	14
29	44
30	60
31	72
32	84
33	96
34	108
35	120
36	80
37	70
38	88
39	104
40	112
41	90
42	132
43	144
44	45
45	66
46	128
47	136
48	152
49	160
50	156
51	168
52	176
53	100
54	27
55	52
56	78
57	184
58	192
59	98
60	102
61	200
62	180

n	a(n)
1	1
2	2
3	4
4	3
5	6
6	8
7	12
8	18
9	24
10	16
11	5
12	10
13	20
14	30
15	32
16	36
17	9
18	15
19	28
20	42
21	40
22	48
23	50
24	54
25	56
26	64
27	7
28	14
29	44
30	60
31	72
32	84
33	96
34	108
35	120
36	80
37	70
38	88
39	104
40	112
41	90
42	132
43	144
44	45
45	66
46	128
47	136
48	152
49	160
50	156
51	168
52	176
53	100
54	27
55	52
56	78
57	184
58	192
59	98
60	102
61	200
62	180

n	a(n)
1	1
2	2
3	4
4	3
5	6
6	8
7	12
8	18
9	24
10	16
11	5
12	10
13	20
14	30
15	32
16	36
17	9
18	15
19	28
20	42
21	40
22	48
23	50
24	54
25	56
26	64
27	7
28	14
29	44
30	60
31	72
32	84
33	96
34	108
35	120
36	80
37	70
38	88
39	104
40	112
41	90
42	132
43	144
44	45
45	66
46	128
47	136
48	152
49	160
50	156
51	168
52	176
53	100
54	27
55	52
56	78
57	184
58	192
59	98
60	102
61	200
62	180