A175502 - cp's OEIS frontend

A175502 a(1) = 1. a(n) = the smallest integer not yet occurring such that each unordered pair {d(a(k)),d(a(k-1))} occurs only once at most, for 2<= k <= n, where d(m) = the number of divisors of m.

n	a(n)
1	1
2	2
3	3
4	4
5	6
6	5
7	12
8	8
9	10
10	16
11	7
12	24
13	9
14	18
15	20
16	30
17	14
18	36
19	11
20	48
21	15
22	60
23	13
24	64
25	21
26	120
27	17
28	144
29	22
30	180
31	19
32	192
33	25
34	49
35	72
36	28
37	80
38	40
39	42
40	81
41	32
42	100
43	54
44	84
45	90
46	112
47	121
48	168
49	44
50	240
51	23
52	360
53	26
54	320
55	45
56	252
57	56
58	210
59	96
60	196

[1, 2, 3, 4, 6, 5, 12, 8, 10, 16, 7, 24, 9, 18, 20, 30, 14, 36, 11, 48, 15, 60, 13, 64, 21, 120, 17, 144, 22, 180, 19, 192, 25, 49, 72, 28, 80, 40, 42, 81, 32, 100, 54, 84, 90, 112, 121, 168, 44, 240, 23, 360, 26, 320, 45, 252, 56, 210, 96, 196]

cp's OEIS Frontend

A175502 a(1) = 1. a(n) = the smallest integer not yet occurring such that each unordered pair {d(a(k)),d(a(k-1))} occurs only once at most, for 2<= k <= n, where d(m) = the number of divisors of m.

Table of values

List of values

n	a(n)
1	1
2	2
3	3
4	4
5	6
6	5
7	12
8	8
9	10
10	16
11	7
12	24
13	9
14	18
15	20
16	30
17	14
18	36
19	11
20	48
21	15
22	60
23	13
24	64
25	21
26	120
27	17
28	144
29	22
30	180
31	19
32	192
33	25
34	49
35	72
36	28
37	80
38	40
39	42
40	81
41	32
42	100
43	54
44	84
45	90
46	112
47	121
48	168
49	44
50	240
51	23
52	360
53	26
54	320
55	45
56	252
57	56
58	210
59	96
60	196

n	a(n)
1	1
2	2
3	3
4	4
5	6
6	5
7	12
8	8
9	10
10	16
11	7
12	24
13	9
14	18
15	20
16	30
17	14
18	36
19	11
20	48
21	15
22	60
23	13
24	64
25	21
26	120
27	17
28	144
29	22
30	180
31	19
32	192
33	25
34	49
35	72
36	28
37	80
38	40
39	42
40	81
41	32
42	100
43	54
44	84
45	90
46	112
47	121
48	168
49	44
50	240
51	23
52	360
53	26
54	320
55	45
56	252
57	56
58	210
59	96
60	196

n	a(n)
1	1
2	2
3	3
4	4
5	6
6	5
7	12
8	8
9	10
10	16
11	7
12	24
13	9
14	18
15	20
16	30
17	14
18	36
19	11
20	48
21	15
22	60
23	13
24	64
25	21
26	120
27	17
28	144
29	22
30	180
31	19
32	192
33	25
34	49
35	72
36	28
37	80
38	40
39	42
40	81
41	32
42	100
43	54
44	84
45	90
46	112
47	121
48	168
49	44
50	240
51	23
52	360
53	26
54	320
55	45
56	252
57	56
58	210
59	96
60	196