A370497 - cp's OEIS frontend

A370497 a(1) = 1; for n > 1, a(n) is smallest unused number such that a(n) is coprime to a(n-1), sopfr(a(n)) is coprime to sopfr(a(n-1)), and Omega(a(n)) does not equal Omega(a(n-1)), where sopfr(k) is the sum of the primes dividing k, with repetition.

n	a(n)
1	1
2	2
3	27
4	4
5	3
6	10
7	11
8	6
9	7
10	8
11	5
12	9
13	13
14	12
15	17
16	14
17	19
18	15
19	23
20	16
21	29
22	18
23	31
24	20
25	21
26	37
27	22
28	41
29	24
30	25
31	28
32	33
33	40
34	39
35	43
36	26
37	45
38	32
39	47
40	30
41	53
42	34
43	59
44	35
45	48
46	49
47	44
48	57
49	52
50	51
51	56
52	55
53	54
54	61
55	36
56	67
57	38
58	63
59	46
60	71
61	42
62	73
63	50
64	79
65	58
66	75
67	62
68	83
69	60
70	89
71	64
72	97
73	65
74	76
75	69
76	68

[1, 2, 27, 4, 3, 10, 11, 6, 7, 8, 5, 9, 13, 12, 17, 14, 19, 15, 23, 16, 29, 18, 31, 20, 21, 37, 22, 41, 24, 25, 28, 33, 40, 39, 43, 26, 45, 32, 47, 30, 53, 34, 59, 35, 48, 49, 44, 57, 52, 51, 56, 55, 54, 61, 36, 67, 38, 63, 46, 71, 42, 73, 50, 79, 58, 75, 62, 83, 60, 89, 64, 97, 65, 76, 69, 68]

cp's OEIS Frontend

A370497 a(1) = 1; for n > 1, a(n) is smallest unused number such that a(n) is coprime to a(n-1), sopfr(a(n)) is coprime to sopfr(a(n-1)), and Omega(a(n)) does not equal Omega(a(n-1)), where sopfr(k) is the sum of the primes dividing k, with repetition.

Table of values

List of values

n	a(n)
1	1
2	2
3	27
4	4
5	3
6	10
7	11
8	6
9	7
10	8
11	5
12	9
13	13
14	12
15	17
16	14
17	19
18	15
19	23
20	16
21	29
22	18
23	31
24	20
25	21
26	37
27	22
28	41
29	24
30	25
31	28
32	33
33	40
34	39
35	43
36	26
37	45
38	32
39	47
40	30
41	53
42	34
43	59
44	35
45	48
46	49
47	44
48	57
49	52
50	51
51	56
52	55
53	54
54	61
55	36
56	67
57	38
58	63
59	46
60	71
61	42
62	73
63	50
64	79
65	58
66	75
67	62
68	83
69	60
70	89
71	64
72	97
73	65
74	76
75	69
76	68

n	a(n)
1	1
2	2
3	27
4	4
5	3
6	10
7	11
8	6
9	7
10	8
11	5
12	9
13	13
14	12
15	17
16	14
17	19
18	15
19	23
20	16
21	29
22	18
23	31
24	20
25	21
26	37
27	22
28	41
29	24
30	25
31	28
32	33
33	40
34	39
35	43
36	26
37	45
38	32
39	47
40	30
41	53
42	34
43	59
44	35
45	48
46	49
47	44
48	57
49	52
50	51
51	56
52	55
53	54
54	61
55	36
56	67
57	38
58	63
59	46
60	71
61	42
62	73
63	50
64	79
65	58
66	75
67	62
68	83
69	60
70	89
71	64
72	97
73	65
74	76
75	69
76	68

n	a(n)
1	1
2	2
3	27
4	4
5	3
6	10
7	11
8	6
9	7
10	8
11	5
12	9
13	13
14	12
15	17
16	14
17	19
18	15
19	23
20	16
21	29
22	18
23	31
24	20
25	21
26	37
27	22
28	41
29	24
30	25
31	28
32	33
33	40
34	39
35	43
36	26
37	45
38	32
39	47
40	30
41	53
42	34
43	59
44	35
45	48
46	49
47	44
48	57
49	52
50	51
51	56
52	55
53	54
54	61
55	36
56	67
57	38
58	63
59	46
60	71
61	42
62	73
63	50
64	79
65	58
66	75
67	62
68	83
69	60
70	89
71	64
72	97
73	65
74	76
75	69
76	68