A005132 - cp's OEIS frontend

A005132 Recamán's sequence (or Recaman's sequence): a(0) = 0; for n > 0, a(n) = a(n-1) - n if nonnegative and not already in the sequence, otherwise a(n) = a(n-1) + n.

n	a(n)
0	0
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	42
25	17
26	43
27	16
28	44
29	15
30	45
31	14
32	46
33	79
34	113
35	78
36	114
37	77
38	39
39	78
40	38
41	79
42	37
43	80
44	36
45	81
46	35
47	82
48	34
49	83
50	33
51	84
52	32
53	85
54	31
55	86
56	30
57	87
58	29
59	88
60	28
61	89
62	27
63	90
64	26
65	91
66	157
67	224
68	156
69	225
70	155

[0, 1, 3, 6, 2, 7, 13, 20, 12, 21, 11, 22, 10, 23, 9, 24, 8, 25, 43, 62, 42, 63, 41, 18, 42, 17, 43, 16, 44, 15, 45, 14, 46, 79, 113, 78, 114, 77, 39, 78, 38, 79, 37, 80, 36, 81, 35, 82, 34, 83, 33, 84, 32, 85, 31, 86, 30, 87, 29, 88, 28, 89, 27, 90, 26, 91, 157, 224, 156, 225, 155]

cp's OEIS Frontend

A005132 Recamán's sequence (or Recaman's sequence): a(0) = 0; for n > 0, a(n) = a(n-1) - n if nonnegative and not already in the sequence, otherwise a(n) = a(n-1) + n.

Table of values

List of values

n	a(n)
0	0
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	42
25	17
26	43
27	16
28	44
29	15
30	45
31	14
32	46
33	79
34	113
35	78
36	114
37	77
38	39
39	78
40	38
41	79
42	37
43	80
44	36
45	81
46	35
47	82
48	34
49	83
50	33
51	84
52	32
53	85
54	31
55	86
56	30
57	87
58	29
59	88
60	28
61	89
62	27
63	90
64	26
65	91
66	157
67	224
68	156
69	225
70	155

n	a(n)
0	0
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	42
25	17
26	43
27	16
28	44
29	15
30	45
31	14
32	46
33	79
34	113
35	78
36	114
37	77
38	39
39	78
40	38
41	79
42	37
43	80
44	36
45	81
46	35
47	82
48	34
49	83
50	33
51	84
52	32
53	85
54	31
55	86
56	30
57	87
58	29
59	88
60	28
61	89
62	27
63	90
64	26
65	91
66	157
67	224
68	156
69	225
70	155

n	a(n)
0	0
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	42
25	17
26	43
27	16
28	44
29	15
30	45
31	14
32	46
33	79
34	113
35	78
36	114
37	77
38	39
39	78
40	38
41	79
42	37
43	80
44	36
45	81
46	35
47	82
48	34
49	83
50	33
51	84
52	32
53	85
54	31
55	86
56	30
57	87
58	29
59	88
60	28
61	89
62	27
63	90
64	26
65	91
66	157
67	224
68	156
69	225
70	155