A064388 - cp's OEIS frontend

A064388 Variation (3) on Recamán's sequence (A005132): set s (the step size) initially equal to 2; to get a(n), we first try to subtract s from a(n-1): a(n) = a(n-1)-s if positive and not already in the sequence, in which case we change s to s+1; if not, a(n) = a(n-1)+s+i, where i >= 0 is the smallest number such that a(n-1)+s+i has not already appeared and now we change s to s+i+1.

n	a(n)
1	1
2	3
3	6
4	2
5	7
6	13
7	20
8	12
9	21
10	11
11	22
12	10
13	23
14	9
15	24
16	8
17	25
18	43
19	62
20	42
21	63
22	41
23	18
24	44
25	17
26	45
27	16
28	46
29	15
30	47
31	14
32	48
33	83
34	119
35	82
36	120
37	81
38	121
39	80
40	38
41	84
42	37
43	85
44	36
45	86
46	35
47	87
48	34
49	88
50	33
51	89
52	32
53	90
54	31
55	91
56	30
57	92
58	29
59	93
60	28
61	94
62	27
63	95
64	26
65	96
66	167
67	239
68	166
69	240

[1, 3, 6, 2, 7, 13, 20, 12, 21, 11, 22, 10, 23, 9, 24, 8, 25, 43, 62, 42, 63, 41, 18, 44, 17, 45, 16, 46, 15, 47, 14, 48, 83, 119, 82, 120, 81, 121, 80, 38, 84, 37, 85, 36, 86, 35, 87, 34, 88, 33, 89, 32, 90, 31, 91, 30, 92, 29, 93, 28, 94, 27, 95, 26, 96, 167, 239, 166, 240]

cp's OEIS Frontend

Table of values

List of values

n	a(n)
1	1
2	3
3	6
4	2
5	7
6	13
7	20
8	12
9	21
10	11
11	22
12	10
13	23
14	9
15	24
16	8
17	25
18	43
19	62
20	42
21	63
22	41
23	18
24	44
25	17
26	45
27	16
28	46
29	15
30	47
31	14
32	48
33	83
34	119
35	82
36	120
37	81
38	121
39	80
40	38
41	84
42	37
43	85
44	36
45	86
46	35
47	87
48	34
49	88
50	33
51	89
52	32
53	90
54	31
55	91
56	30
57	92
58	29
59	93
60	28
61	94
62	27
63	95
64	26
65	96
66	167
67	239
68	166
69	240

n	a(n)
1	1
2	3
3	6
4	2
5	7
6	13
7	20
8	12
9	21
10	11
11	22
12	10
13	23
14	9
15	24
16	8
17	25
18	43
19	62
20	42
21	63
22	41
23	18
24	44
25	17
26	45
27	16
28	46
29	15
30	47
31	14
32	48
33	83
34	119
35	82
36	120
37	81
38	121
39	80
40	38
41	84
42	37
43	85
44	36
45	86
46	35
47	87
48	34
49	88
50	33
51	89
52	32
53	90
54	31
55	91
56	30
57	92
58	29
59	93
60	28
61	94
62	27
63	95
64	26
65	96
66	167
67	239
68	166
69	240

n	a(n)
1	1
2	3
3	6
4	2
5	7
6	13
7	20
8	12
9	21
10	11
11	22
12	10
13	23
14	9
15	24
16	8
17	25
18	43
19	62
20	42
21	63
22	41
23	18
24	44
25	17
26	45
27	16
28	46
29	15
30	47
31	14
32	48
33	83
34	119
35	82
36	120
37	81
38	121
39	80
40	38
41	84
42	37
43	85
44	36
45	86
46	35
47	87
48	34
49	88
50	33
51	89
52	32
53	90
54	31
55	91
56	30
57	92
58	29
59	93
60	28
61	94
62	27
63	95
64	26
65	96
66	167
67	239
68	166
69	240