A066199 - cp's OEIS frontend

A066199 a(1) = 1; for n > 1, a(n) = a(n-1)-(n+1) if this is positive and has not already appeared in the sequence, otherwise a(n) = a(n-1)+(n+1).

n	a(n)
1	1
2	4
3	8
4	3
5	9
6	2
7	10
8	19
9	29
10	18
11	6
12	19
13	5
14	20
15	36
16	53
17	35
18	16
19	36
20	15
21	37
22	14
23	38
24	13
25	39
26	12
27	40
28	11
29	41
30	72
31	104
32	71
33	105
34	70
35	34
36	71
37	33
38	72
39	32
40	73
41	31
42	74
43	30
44	75
45	121
46	168
47	120
48	169
49	119
50	68
51	120
52	67
53	121
54	66
55	122
56	65
57	7
58	66
59	126
60	187
61	125
62	62
63	126
64	61
65	127
66	60
67	128

[1, 4, 8, 3, 9, 2, 10, 19, 29, 18, 6, 19, 5, 20, 36, 53, 35, 16, 36, 15, 37, 14, 38, 13, 39, 12, 40, 11, 41, 72, 104, 71, 105, 70, 34, 71, 33, 72, 32, 73, 31, 74, 30, 75, 121, 168, 120, 169, 119, 68, 120, 67, 121, 66, 122, 65, 7, 66, 126, 187, 125, 62, 126, 61, 127, 60, 128]

cp's OEIS Frontend

A066199 a(1) = 1; for n > 1, a(n) = a(n-1)-(n+1) if this is positive and has not already appeared in the sequence, otherwise a(n) = a(n-1)+(n+1).

Table of values

List of values

n	a(n)
1	1
2	4
3	8
4	3
5	9
6	2
7	10
8	19
9	29
10	18
11	6
12	19
13	5
14	20
15	36
16	53
17	35
18	16
19	36
20	15
21	37
22	14
23	38
24	13
25	39
26	12
27	40
28	11
29	41
30	72
31	104
32	71
33	105
34	70
35	34
36	71
37	33
38	72
39	32
40	73
41	31
42	74
43	30
44	75
45	121
46	168
47	120
48	169
49	119
50	68
51	120
52	67
53	121
54	66
55	122
56	65
57	7
58	66
59	126
60	187
61	125
62	62
63	126
64	61
65	127
66	60
67	128

n	a(n)
1	1
2	4
3	8
4	3
5	9
6	2
7	10
8	19
9	29
10	18
11	6
12	19
13	5
14	20
15	36
16	53
17	35
18	16
19	36
20	15
21	37
22	14
23	38
24	13
25	39
26	12
27	40
28	11
29	41
30	72
31	104
32	71
33	105
34	70
35	34
36	71
37	33
38	72
39	32
40	73
41	31
42	74
43	30
44	75
45	121
46	168
47	120
48	169
49	119
50	68
51	120
52	67
53	121
54	66
55	122
56	65
57	7
58	66
59	126
60	187
61	125
62	62
63	126
64	61
65	127
66	60
67	128

n	a(n)
1	1
2	4
3	8
4	3
5	9
6	2
7	10
8	19
9	29
10	18
11	6
12	19
13	5
14	20
15	36
16	53
17	35
18	16
19	36
20	15
21	37
22	14
23	38
24	13
25	39
26	12
27	40
28	11
29	41
30	72
31	104
32	71
33	105
34	70
35	34
36	71
37	33
38	72
39	32
40	73
41	31
42	74
43	30
44	75
45	121
46	168
47	120
48	169
49	119
50	68
51	120
52	67
53	121
54	66
55	122
56	65
57	7
58	66
59	126
60	187
61	125
62	62
63	126
64	61
65	127
66	60
67	128