A372975 - cp's OEIS frontend

A372975 a(1) = 1, a(2) = 2; for n > 2, a(n) is the smallest unused positive number such that a(n) shares a factor with a(n-1) while omega(a(n)) does not equal omega(a(n-1)).

n	a(n)
1	1
2	2
3	6
4	3
5	12
6	4
7	10
8	5
9	15
10	9
11	18
12	8
13	14
14	7
15	21
16	27
17	24
18	16
19	20
20	25
21	30
22	22
23	11
24	33
25	42
26	26
27	13
28	39
29	60
30	28
31	32
32	34
33	17
34	51
35	66
36	36
37	64
38	38
39	19
40	57
41	78
42	40
43	70
44	35
45	49
46	56
47	84
48	44
49	90
50	45
51	81
52	48
53	102
54	46
55	23
56	69
57	105
58	50
59	110
60	52
61	114
62	54
63	120
64	55
65	121
66	77
67	126
68	58
69	29
70	87
71	132
72	62
73	31
74	93
75	138

[1, 2, 6, 3, 12, 4, 10, 5, 15, 9, 18, 8, 14, 7, 21, 27, 24, 16, 20, 25, 30, 22, 11, 33, 42, 26, 13, 39, 60, 28, 32, 34, 17, 51, 66, 36, 64, 38, 19, 57, 78, 40, 70, 35, 49, 56, 84, 44, 90, 45, 81, 48, 102, 46, 23, 69, 105, 50, 110, 52, 114, 54, 120, 55, 121, 77, 126, 58, 29, 87, 132, 62, 31, 93, 138]

cp's OEIS Frontend

A372975 a(1) = 1, a(2) = 2; for n > 2, a(n) is the smallest unused positive number such that a(n) shares a factor with a(n-1) while omega(a(n)) does not equal omega(a(n-1)).

Table of values

List of values

n	a(n)
1	1
2	2
3	6
4	3
5	12
6	4
7	10
8	5
9	15
10	9
11	18
12	8
13	14
14	7
15	21
16	27
17	24
18	16
19	20
20	25
21	30
22	22
23	11
24	33
25	42
26	26
27	13
28	39
29	60
30	28
31	32
32	34
33	17
34	51
35	66
36	36
37	64
38	38
39	19
40	57
41	78
42	40
43	70
44	35
45	49
46	56
47	84
48	44
49	90
50	45
51	81
52	48
53	102
54	46
55	23
56	69
57	105
58	50
59	110
60	52
61	114
62	54
63	120
64	55
65	121
66	77
67	126
68	58
69	29
70	87
71	132
72	62
73	31
74	93
75	138

n	a(n)
1	1
2	2
3	6
4	3
5	12
6	4
7	10
8	5
9	15
10	9
11	18
12	8
13	14
14	7
15	21
16	27
17	24
18	16
19	20
20	25
21	30
22	22
23	11
24	33
25	42
26	26
27	13
28	39
29	60
30	28
31	32
32	34
33	17
34	51
35	66
36	36
37	64
38	38
39	19
40	57
41	78
42	40
43	70
44	35
45	49
46	56
47	84
48	44
49	90
50	45
51	81
52	48
53	102
54	46
55	23
56	69
57	105
58	50
59	110
60	52
61	114
62	54
63	120
64	55
65	121
66	77
67	126
68	58
69	29
70	87
71	132
72	62
73	31
74	93
75	138

n	a(n)
1	1
2	2
3	6
4	3
5	12
6	4
7	10
8	5
9	15
10	9
11	18
12	8
13	14
14	7
15	21
16	27
17	24
18	16
19	20
20	25
21	30
22	22
23	11
24	33
25	42
26	26
27	13
28	39
29	60
30	28
31	32
32	34
33	17
34	51
35	66
36	36
37	64
38	38
39	19
40	57
41	78
42	40
43	70
44	35
45	49
46	56
47	84
48	44
49	90
50	45
51	81
52	48
53	102
54	46
55	23
56	69
57	105
58	50
59	110
60	52
61	114
62	54
63	120
64	55
65	121
66	77
67	126
68	58
69	29
70	87
71	132
72	62
73	31
74	93
75	138