A169747 - cp's OEIS frontend

A169747 a(1)=1; thereafter, a(2n)=a(n), a(2n+1) = a(2n-1)-a(n) if that number is positive and not already in the sequence, otherwise a(2n+1) = a(2n-1)+a(n).

n	a(n)
1	1
2	1
3	2
4	1
5	3
6	2
7	5
8	1
9	4
10	3
11	7
12	2
13	9
14	5
15	14
16	1
17	13
18	4
19	17
20	3
21	20
22	7
23	27
24	2
25	25
26	9
27	16
28	5
29	11
30	14
31	25
32	1
33	24
34	13
35	37
36	4
37	33
38	17
39	50
40	3
41	47
42	20
43	67
44	7
45	60
46	27
47	87
48	2
49	85
50	25
51	110
52	9
53	101
54	16
55	117
56	5
57	112
58	11
59	123
60	14
61	109
62	25
63	84
64	1
65	83
66	24
67	59
68	13
69	46
70	37
71	83
72	4
73	79
74	33
75	112
76	17
77	95

[1, 1, 2, 1, 3, 2, 5, 1, 4, 3, 7, 2, 9, 5, 14, 1, 13, 4, 17, 3, 20, 7, 27, 2, 25, 9, 16, 5, 11, 14, 25, 1, 24, 13, 37, 4, 33, 17, 50, 3, 47, 20, 67, 7, 60, 27, 87, 2, 85, 25, 110, 9, 101, 16, 117, 5, 112, 11, 123, 14, 109, 25, 84, 1, 83, 24, 59, 13, 46, 37, 83, 4, 79, 33, 112, 17, 95]

cp's OEIS Frontend

A169747 a(1)=1; thereafter, a(2n)=a(n), a(2n+1) = a(2n-1)-a(n) if that number is positive and not already in the sequence, otherwise a(2n+1) = a(2n-1)+a(n).

Table of values

List of values

n	a(n)
1	1
2	1
3	2
4	1
5	3
6	2
7	5
8	1
9	4
10	3
11	7
12	2
13	9
14	5
15	14
16	1
17	13
18	4
19	17
20	3
21	20
22	7
23	27
24	2
25	25
26	9
27	16
28	5
29	11
30	14
31	25
32	1
33	24
34	13
35	37
36	4
37	33
38	17
39	50
40	3
41	47
42	20
43	67
44	7
45	60
46	27
47	87
48	2
49	85
50	25
51	110
52	9
53	101
54	16
55	117
56	5
57	112
58	11
59	123
60	14
61	109
62	25
63	84
64	1
65	83
66	24
67	59
68	13
69	46
70	37
71	83
72	4
73	79
74	33
75	112
76	17
77	95

n	a(n)
1	1
2	1
3	2
4	1
5	3
6	2
7	5
8	1
9	4
10	3
11	7
12	2
13	9
14	5
15	14
16	1
17	13
18	4
19	17
20	3
21	20
22	7
23	27
24	2
25	25
26	9
27	16
28	5
29	11
30	14
31	25
32	1
33	24
34	13
35	37
36	4
37	33
38	17
39	50
40	3
41	47
42	20
43	67
44	7
45	60
46	27
47	87
48	2
49	85
50	25
51	110
52	9
53	101
54	16
55	117
56	5
57	112
58	11
59	123
60	14
61	109
62	25
63	84
64	1
65	83
66	24
67	59
68	13
69	46
70	37
71	83
72	4
73	79
74	33
75	112
76	17
77	95

n	a(n)
1	1
2	1
3	2
4	1
5	3
6	2
7	5
8	1
9	4
10	3
11	7
12	2
13	9
14	5
15	14
16	1
17	13
18	4
19	17
20	3
21	20
22	7
23	27
24	2
25	25
26	9
27	16
28	5
29	11
30	14
31	25
32	1
33	24
34	13
35	37
36	4
37	33
38	17
39	50
40	3
41	47
42	20
43	67
44	7
45	60
46	27
47	87
48	2
49	85
50	25
51	110
52	9
53	101
54	16
55	117
56	5
57	112
58	11
59	123
60	14
61	109
62	25
63	84
64	1
65	83
66	24
67	59
68	13
69	46
70	37
71	83
72	4
73	79
74	33
75	112
76	17
77	95