A381420 - cp's OEIS frontend

A381420 a(1) = 1, a(2) = 3; for n > 2, a(n) is the smallest unused positive number that shares a factor with a(n-1) and has a different binary weight than a(n-1).

n	a(n)
1	1
2	3
3	15
4	5
5	25
6	10
7	2
8	6
9	4
10	12
11	8
12	14
13	16
14	18
15	21
16	9
17	27
18	24
19	22
20	20
21	26
22	30
23	28
24	32
25	34
26	38
27	36
28	39
29	13
30	65
31	35
32	40
33	42
34	33
35	11
36	55
37	44
38	46
39	48
40	45
41	50
42	54
43	52
44	58
45	56
46	60
47	62
48	64
49	66
50	51
51	17
52	85
53	68
54	70
55	63
56	7
57	77
58	49
59	91
60	78
61	69
62	23
63	115
64	75
65	72
66	57
67	19
68	95
69	76
70	80
71	74
72	86
73	82
74	90

[1, 3, 15, 5, 25, 10, 2, 6, 4, 12, 8, 14, 16, 18, 21, 9, 27, 24, 22, 20, 26, 30, 28, 32, 34, 38, 36, 39, 13, 65, 35, 40, 42, 33, 11, 55, 44, 46, 48, 45, 50, 54, 52, 58, 56, 60, 62, 64, 66, 51, 17, 85, 68, 70, 63, 7, 77, 49, 91, 78, 69, 23, 115, 75, 72, 57, 19, 95, 76, 80, 74, 86, 82, 90]

cp's OEIS Frontend

A381420 a(1) = 1, a(2) = 3; for n > 2, a(n) is the smallest unused positive number that shares a factor with a(n-1) and has a different binary weight than a(n-1).

Table of values

List of values

n	a(n)
1	1
2	3
3	15
4	5
5	25
6	10
7	2
8	6
9	4
10	12
11	8
12	14
13	16
14	18
15	21
16	9
17	27
18	24
19	22
20	20
21	26
22	30
23	28
24	32
25	34
26	38
27	36
28	39
29	13
30	65
31	35
32	40
33	42
34	33
35	11
36	55
37	44
38	46
39	48
40	45
41	50
42	54
43	52
44	58
45	56
46	60
47	62
48	64
49	66
50	51
51	17
52	85
53	68
54	70
55	63
56	7
57	77
58	49
59	91
60	78
61	69
62	23
63	115
64	75
65	72
66	57
67	19
68	95
69	76
70	80
71	74
72	86
73	82
74	90

n	a(n)
1	1
2	3
3	15
4	5
5	25
6	10
7	2
8	6
9	4
10	12
11	8
12	14
13	16
14	18
15	21
16	9
17	27
18	24
19	22
20	20
21	26
22	30
23	28
24	32
25	34
26	38
27	36
28	39
29	13
30	65
31	35
32	40
33	42
34	33
35	11
36	55
37	44
38	46
39	48
40	45
41	50
42	54
43	52
44	58
45	56
46	60
47	62
48	64
49	66
50	51
51	17
52	85
53	68
54	70
55	63
56	7
57	77
58	49
59	91
60	78
61	69
62	23
63	115
64	75
65	72
66	57
67	19
68	95
69	76
70	80
71	74
72	86
73	82
74	90

n	a(n)
1	1
2	3
3	15
4	5
5	25
6	10
7	2
8	6
9	4
10	12
11	8
12	14
13	16
14	18
15	21
16	9
17	27
18	24
19	22
20	20
21	26
22	30
23	28
24	32
25	34
26	38
27	36
28	39
29	13
30	65
31	35
32	40
33	42
34	33
35	11
36	55
37	44
38	46
39	48
40	45
41	50
42	54
43	52
44	58
45	56
46	60
47	62
48	64
49	66
50	51
51	17
52	85
53	68
54	70
55	63
56	7
57	77
58	49
59	91
60	78
61	69
62	23
63	115
64	75
65	72
66	57
67	19
68	95
69	76
70	80
71	74
72	86
73	82
74	90