A372974 - cp's OEIS frontend

A372974 a(1) = 1, a(2) = 2; for n > 2, a(n) is the smallest unused positive number such that a(n) is coprime to a(n-1) and omega(a(n)) does not equal omega(a(n-1)).

n	a(n)
1	1
2	2
3	15
4	4
5	21
6	5
7	6
8	7
9	10
10	3
11	14
12	9
13	20
14	11
15	12
16	13
17	18
18	17
19	22
20	19
21	24
22	23
23	26
24	25
25	28
26	27
27	34
28	29
29	30
30	31
31	33
32	8
33	35
34	16
35	39
36	32
37	45
38	37
39	36
40	41
41	38
42	43
43	40
44	47
45	42
46	53
47	44
48	49
49	46
50	59
51	48
52	61
53	50
54	67
55	51
56	64
57	55
58	71
59	52
60	73
61	54
62	79
63	56
64	81
65	58
66	83
67	57
68	70
69	69
70	89
71	60
72	77
73	78
74	85
75	66
76	65
77	84

[1, 2, 15, 4, 21, 5, 6, 7, 10, 3, 14, 9, 20, 11, 12, 13, 18, 17, 22, 19, 24, 23, 26, 25, 28, 27, 34, 29, 30, 31, 33, 8, 35, 16, 39, 32, 45, 37, 36, 41, 38, 43, 40, 47, 42, 53, 44, 49, 46, 59, 48, 61, 50, 67, 51, 64, 55, 71, 52, 73, 54, 79, 56, 81, 58, 83, 57, 70, 69, 89, 60, 77, 78, 85, 66, 65, 84]

cp's OEIS Frontend

A372974 a(1) = 1, a(2) = 2; for n > 2, a(n) is the smallest unused positive number such that a(n) is coprime to a(n-1) and omega(a(n)) does not equal omega(a(n-1)).

Table of values

List of values

n	a(n)
1	1
2	2
3	15
4	4
5	21
6	5
7	6
8	7
9	10
10	3
11	14
12	9
13	20
14	11
15	12
16	13
17	18
18	17
19	22
20	19
21	24
22	23
23	26
24	25
25	28
26	27
27	34
28	29
29	30
30	31
31	33
32	8
33	35
34	16
35	39
36	32
37	45
38	37
39	36
40	41
41	38
42	43
43	40
44	47
45	42
46	53
47	44
48	49
49	46
50	59
51	48
52	61
53	50
54	67
55	51
56	64
57	55
58	71
59	52
60	73
61	54
62	79
63	56
64	81
65	58
66	83
67	57
68	70
69	69
70	89
71	60
72	77
73	78
74	85
75	66
76	65
77	84

n	a(n)
1	1
2	2
3	15
4	4
5	21
6	5
7	6
8	7
9	10
10	3
11	14
12	9
13	20
14	11
15	12
16	13
17	18
18	17
19	22
20	19
21	24
22	23
23	26
24	25
25	28
26	27
27	34
28	29
29	30
30	31
31	33
32	8
33	35
34	16
35	39
36	32
37	45
38	37
39	36
40	41
41	38
42	43
43	40
44	47
45	42
46	53
47	44
48	49
49	46
50	59
51	48
52	61
53	50
54	67
55	51
56	64
57	55
58	71
59	52
60	73
61	54
62	79
63	56
64	81
65	58
66	83
67	57
68	70
69	69
70	89
71	60
72	77
73	78
74	85
75	66
76	65
77	84

n	a(n)
1	1
2	2
3	15
4	4
5	21
6	5
7	6
8	7
9	10
10	3
11	14
12	9
13	20
14	11
15	12
16	13
17	18
18	17
19	22
20	19
21	24
22	23
23	26
24	25
25	28
26	27
27	34
28	29
29	30
30	31
31	33
32	8
33	35
34	16
35	39
36	32
37	45
38	37
39	36
40	41
41	38
42	43
43	40
44	47
45	42
46	53
47	44
48	49
49	46
50	59
51	48
52	61
53	50
54	67
55	51
56	64
57	55
58	71
59	52
60	73
61	54
62	79
63	56
64	81
65	58
66	83
67	57
68	70
69	69
70	89
71	60
72	77
73	78
74	85
75	66
76	65
77	84