A277558 - cp's OEIS frontend

A277558 A variation on Recamán's sequence (A005132): to get a(n), we first try to subtract n from a(n-1): a(n) = a(n-1)-n if positive and not already in the sequence; if not then a(n) = a(n-1)+n-i, where i >= 0 is the smallest number such that a(n-1)+n-i has not already appeared.

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	40
25	15
26	39
27	66
28	38
29	67
30	37
31	68
32	36
33	69
34	35
35	70
36	34
37	71
38	33
39	72
40	32
41	73
42	31
43	74
44	30
45	75
46	29
47	76
48	28
49	77
50	27
51	78
52	26
53	79
54	133
55	188
56	132
57	189
58	131
59	190
60	130
61	191
62	129
63	192

[0, 1, 3, 6, 2, 7, 13, 20, 12, 21, 11, 22, 10, 23, 9, 24, 8, 25, 43, 62, 42, 63, 41, 18, 40, 15, 39, 66, 38, 67, 37, 68, 36, 69, 35, 70, 34, 71, 33, 72, 32, 73, 31, 74, 30, 75, 29, 76, 28, 77, 27, 78, 26, 79, 133, 188, 132, 189, 131, 190, 130, 191, 129, 192]

cp's OEIS Frontend

A277558 A variation on Recamán's sequence (A005132): to get a(n), we first try to subtract n from a(n-1): a(n) = a(n-1)-n if positive and not already in the sequence; if not then a(n) = a(n-1)+n-i, where i >= 0 is the smallest number such that a(n-1)+n-i has not already appeared.

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	40
25	15
26	39
27	66
28	38
29	67
30	37
31	68
32	36
33	69
34	35
35	70
36	34
37	71
38	33
39	72
40	32
41	73
42	31
43	74
44	30
45	75
46	29
47	76
48	28
49	77
50	27
51	78
52	26
53	79
54	133
55	188
56	132
57	189
58	131
59	190
60	130
61	191
62	129
63	192

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	40
25	15
26	39
27	66
28	38
29	67
30	37
31	68
32	36
33	69
34	35
35	70
36	34
37	71
38	33
39	72
40	32
41	73
42	31
43	74
44	30
45	75
46	29
47	76
48	28
49	77
50	27
51	78
52	26
53	79
54	133
55	188
56	132
57	189
58	131
59	190
60	130
61	191
62	129
63	192

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	40
25	15
26	39
27	66
28	38
29	67
30	37
31	68
32	36
33	69
34	35
35	70
36	34
37	71
38	33
39	72
40	32
41	73
42	31
43	74
44	30
45	75
46	29
47	76
48	28
49	77
50	27
51	78
52	26
53	79
54	133
55	188
56	132
57	189
58	131
59	190
60	130
61	191
62	129
63	192