A373623 - cp's OEIS frontend

A373623 a(n) = n for n <= 3; for n > 3, a(n) is the smallest unused positive number that shares a factor with the most recently appearing even number if a(n-1) is odd, otherwise it shares a factor with the most recently appearing odd number if a(n-1) is even.

n	a(n)
1	1
2	2
3	3
4	4
5	6
6	9
7	8
8	12
9	15
10	10
11	5
12	14
13	20
14	25
15	16
16	30
17	35
18	18
19	7
20	21
21	22
22	24
23	27
24	26
25	33
26	13
27	28
28	39
29	32
30	36
31	42
32	45
33	34
34	40
35	48
36	50
37	51
38	38
39	17
40	19
41	44
42	57
43	11
44	46
45	55
46	23
47	52
48	69
49	54
50	60
51	63
52	56
53	49
54	58
55	70
56	77
57	62
58	66
59	84
60	88
61	91
62	64
63	65
64	68
65	75
66	72
67	78
68	80
69	81
70	74
71	87
72	37
73	76
74	111
75	82
76	90
77	93

[1, 2, 3, 4, 6, 9, 8, 12, 15, 10, 5, 14, 20, 25, 16, 30, 35, 18, 7, 21, 22, 24, 27, 26, 33, 13, 28, 39, 32, 36, 42, 45, 34, 40, 48, 50, 51, 38, 17, 19, 44, 57, 11, 46, 55, 23, 52, 69, 54, 60, 63, 56, 49, 58, 70, 77, 62, 66, 84, 88, 91, 64, 65, 68, 75, 72, 78, 80, 81, 74, 87, 37, 76, 111, 82, 90, 93]

cp's OEIS Frontend

A373623 a(n) = n for n <= 3; for n > 3, a(n) is the smallest unused positive number that shares a factor with the most recently appearing even number if a(n-1) is odd, otherwise it shares a factor with the most recently appearing odd number if a(n-1) is even.

Table of values

List of values

n	a(n)
1	1
2	2
3	3
4	4
5	6
6	9
7	8
8	12
9	15
10	10
11	5
12	14
13	20
14	25
15	16
16	30
17	35
18	18
19	7
20	21
21	22
22	24
23	27
24	26
25	33
26	13
27	28
28	39
29	32
30	36
31	42
32	45
33	34
34	40
35	48
36	50
37	51
38	38
39	17
40	19
41	44
42	57
43	11
44	46
45	55
46	23
47	52
48	69
49	54
50	60
51	63
52	56
53	49
54	58
55	70
56	77
57	62
58	66
59	84
60	88
61	91
62	64
63	65
64	68
65	75
66	72
67	78
68	80
69	81
70	74
71	87
72	37
73	76
74	111
75	82
76	90
77	93

n	a(n)
1	1
2	2
3	3
4	4
5	6
6	9
7	8
8	12
9	15
10	10
11	5
12	14
13	20
14	25
15	16
16	30
17	35
18	18
19	7
20	21
21	22
22	24
23	27
24	26
25	33
26	13
27	28
28	39
29	32
30	36
31	42
32	45
33	34
34	40
35	48
36	50
37	51
38	38
39	17
40	19
41	44
42	57
43	11
44	46
45	55
46	23
47	52
48	69
49	54
50	60
51	63
52	56
53	49
54	58
55	70
56	77
57	62
58	66
59	84
60	88
61	91
62	64
63	65
64	68
65	75
66	72
67	78
68	80
69	81
70	74
71	87
72	37
73	76
74	111
75	82
76	90
77	93

n	a(n)
1	1
2	2
3	3
4	4
5	6
6	9
7	8
8	12
9	15
10	10
11	5
12	14
13	20
14	25
15	16
16	30
17	35
18	18
19	7
20	21
21	22
22	24
23	27
24	26
25	33
26	13
27	28
28	39
29	32
30	36
31	42
32	45
33	34
34	40
35	48
36	50
37	51
38	38
39	17
40	19
41	44
42	57
43	11
44	46
45	55
46	23
47	52
48	69
49	54
50	60
51	63
52	56
53	49
54	58
55	70
56	77
57	62
58	66
59	84
60	88
61	91
62	64
63	65
64	68
65	75
66	72
67	78
68	80
69	81
70	74
71	87
72	37
73	76
74	111
75	82
76	90
77	93