A373698 - cp's OEIS frontend

A373698 a(n) = n for n <= 3; for n > 3, a(n) is the smallest unused positive number that shares a factor with the largest odd divisor of a(n-1).

n	a(n)
1	1
2	2
3	3
4	6
5	9
6	12
7	15
8	5
9	10
10	20
11	25
12	30
13	18
14	21
15	7
16	14
17	28
18	35
19	40
20	45
21	24
22	27
23	33
24	11
25	22
26	44
27	55
28	50
29	60
30	36
31	39
32	13
33	26
34	52
35	65
36	70
37	42
38	48
39	51
40	17
41	34
42	68
43	85
44	75
45	54
46	57
47	19
48	38
49	76
50	95
51	80
52	90
53	63
54	49
55	56
56	77
57	66
58	69
59	23
60	46
61	92
62	115
63	100
64	105
65	72
66	78
67	81
68	84
69	87
70	29
71	58
72	116
73	145
74	110

[1, 2, 3, 6, 9, 12, 15, 5, 10, 20, 25, 30, 18, 21, 7, 14, 28, 35, 40, 45, 24, 27, 33, 11, 22, 44, 55, 50, 60, 36, 39, 13, 26, 52, 65, 70, 42, 48, 51, 17, 34, 68, 85, 75, 54, 57, 19, 38, 76, 95, 80, 90, 63, 49, 56, 77, 66, 69, 23, 46, 92, 115, 100, 105, 72, 78, 81, 84, 87, 29, 58, 116, 145, 110]

cp's OEIS Frontend

A373698 a(n) = n for n <= 3; for n > 3, a(n) is the smallest unused positive number that shares a factor with the largest odd divisor of a(n-1).

Table of values

List of values

n	a(n)
1	1
2	2
3	3
4	6
5	9
6	12
7	15
8	5
9	10
10	20
11	25
12	30
13	18
14	21
15	7
16	14
17	28
18	35
19	40
20	45
21	24
22	27
23	33
24	11
25	22
26	44
27	55
28	50
29	60
30	36
31	39
32	13
33	26
34	52
35	65
36	70
37	42
38	48
39	51
40	17
41	34
42	68
43	85
44	75
45	54
46	57
47	19
48	38
49	76
50	95
51	80
52	90
53	63
54	49
55	56
56	77
57	66
58	69
59	23
60	46
61	92
62	115
63	100
64	105
65	72
66	78
67	81
68	84
69	87
70	29
71	58
72	116
73	145
74	110

n	a(n)
1	1
2	2
3	3
4	6
5	9
6	12
7	15
8	5
9	10
10	20
11	25
12	30
13	18
14	21
15	7
16	14
17	28
18	35
19	40
20	45
21	24
22	27
23	33
24	11
25	22
26	44
27	55
28	50
29	60
30	36
31	39
32	13
33	26
34	52
35	65
36	70
37	42
38	48
39	51
40	17
41	34
42	68
43	85
44	75
45	54
46	57
47	19
48	38
49	76
50	95
51	80
52	90
53	63
54	49
55	56
56	77
57	66
58	69
59	23
60	46
61	92
62	115
63	100
64	105
65	72
66	78
67	81
68	84
69	87
70	29
71	58
72	116
73	145
74	110

n	a(n)
1	1
2	2
3	3
4	6
5	9
6	12
7	15
8	5
9	10
10	20
11	25
12	30
13	18
14	21
15	7
16	14
17	28
18	35
19	40
20	45
21	24
22	27
23	33
24	11
25	22
26	44
27	55
28	50
29	60
30	36
31	39
32	13
33	26
34	52
35	65
36	70
37	42
38	48
39	51
40	17
41	34
42	68
43	85
44	75
45	54
46	57
47	19
48	38
49	76
50	95
51	80
52	90
53	63
54	49
55	56
56	77
57	66
58	69
59	23
60	46
61	92
62	115
63	100
64	105
65	72
66	78
67	81
68	84
69	87
70	29
71	58
72	116
73	145
74	110