A128204 - cp's OEIS frontend

A128204 a(0) = 0; a(n) = a(n-1) - (2n-1) if that number is positive and not already in the sequence, otherwise a(n) = a(n-1) + (2n-1).

n	a(n)
0	0
1	1
2	4
3	9
4	2
5	11
6	22
7	35
8	20
9	3
10	22
11	43
12	66
13	41
14	14
15	43
16	12
17	45
18	10
19	47
20	8
21	49
22	6
23	51
24	98
25	147
26	96
27	149
28	94
29	37
30	96
31	157
32	220
33	155
34	88
35	19
36	90
37	17
38	92
39	15
40	94
41	13
42	96
43	181
44	268
45	179
46	270
47	177
48	82
49	179
50	80
51	181
52	78
53	183
54	76
55	185
56	74
57	187
58	72
59	189
60	70
61	191
62	68
63	193
64	320

[0, 1, 4, 9, 2, 11, 22, 35, 20, 3, 22, 43, 66, 41, 14, 43, 12, 45, 10, 47, 8, 49, 6, 51, 98, 147, 96, 149, 94, 37, 96, 157, 220, 155, 88, 19, 90, 17, 92, 15, 94, 13, 96, 181, 268, 179, 270, 177, 82, 179, 80, 181, 78, 183, 76, 185, 74, 187, 72, 189, 70, 191, 68, 193, 320]

cp's OEIS Frontend

A128204 a(0) = 0; a(n) = a(n-1) - (2n-1) if that number is positive and not already in the sequence, otherwise a(n) = a(n-1) + (2n-1).

Table of values

List of values

n	a(n)
0	0
1	1
2	4
3	9
4	2
5	11
6	22
7	35
8	20
9	3
10	22
11	43
12	66
13	41
14	14
15	43
16	12
17	45
18	10
19	47
20	8
21	49
22	6
23	51
24	98
25	147
26	96
27	149
28	94
29	37
30	96
31	157
32	220
33	155
34	88
35	19
36	90
37	17
38	92
39	15
40	94
41	13
42	96
43	181
44	268
45	179
46	270
47	177
48	82
49	179
50	80
51	181
52	78
53	183
54	76
55	185
56	74
57	187
58	72
59	189
60	70
61	191
62	68
63	193
64	320

n	a(n)
0	0
1	1
2	4
3	9
4	2
5	11
6	22
7	35
8	20
9	3
10	22
11	43
12	66
13	41
14	14
15	43
16	12
17	45
18	10
19	47
20	8
21	49
22	6
23	51
24	98
25	147
26	96
27	149
28	94
29	37
30	96
31	157
32	220
33	155
34	88
35	19
36	90
37	17
38	92
39	15
40	94
41	13
42	96
43	181
44	268
45	179
46	270
47	177
48	82
49	179
50	80
51	181
52	78
53	183
54	76
55	185
56	74
57	187
58	72
59	189
60	70
61	191
62	68
63	193
64	320

n	a(n)
0	0
1	1
2	4
3	9
4	2
5	11
6	22
7	35
8	20
9	3
10	22
11	43
12	66
13	41
14	14
15	43
16	12
17	45
18	10
19	47
20	8
21	49
22	6
23	51
24	98
25	147
26	96
27	149
28	94
29	37
30	96
31	157
32	220
33	155
34	88
35	19
36	90
37	17
38	92
39	15
40	94
41	13
42	96
43	181
44	268
45	179
46	270
47	177
48	82
49	179
50	80
51	181
52	78
53	183
54	76
55	185
56	74
57	187
58	72
59	189
60	70
61	191
62	68
63	193
64	320