A117120 - cp's OEIS frontend

A117120 a(1)=1. a(n) is smallest positive integer not occurring earlier in the sequence where a(n) is congruent to -1 (mod a(n-1)).

n	a(n)
1	1
2	2
3	3
4	5
5	4
6	7
7	6
8	11
9	10
10	9
11	8
12	15
13	14
14	13
15	12
16	23
17	22
18	21
19	20
20	19
21	18
22	17
23	16
24	31
25	30
26	29
27	28
28	27
29	26
30	25
31	24
32	47
33	46
34	45
35	44
36	43
37	42
38	41
39	40
40	39
41	38
42	37
43	36
44	35
45	34
46	33
47	32
48	63
49	62
50	61
51	60
52	59
53	58
54	57
55	56
56	55
57	54
58	53
59	52
60	51
61	50
62	49
63	48
64	95
65	94
66	93
67	92
68	91
69	90
70	89
71	88
72	87

[1, 2, 3, 5, 4, 7, 6, 11, 10, 9, 8, 15, 14, 13, 12, 23, 22, 21, 20, 19, 18, 17, 16, 31, 30, 29, 28, 27, 26, 25, 24, 47, 46, 45, 44, 43, 42, 41, 40, 39, 38, 37, 36, 35, 34, 33, 32, 63, 62, 61, 60, 59, 58, 57, 56, 55, 54, 53, 52, 51, 50, 49, 48, 95, 94, 93, 92, 91, 90, 89, 88, 87]

cp's OEIS Frontend

A117120 a(1)=1. a(n) is smallest positive integer not occurring earlier in the sequence where a(n) is congruent to -1 (mod a(n-1)).

Table of values

List of values

n	a(n)
1	1
2	2
3	3
4	5
5	4
6	7
7	6
8	11
9	10
10	9
11	8
12	15
13	14
14	13
15	12
16	23
17	22
18	21
19	20
20	19
21	18
22	17
23	16
24	31
25	30
26	29
27	28
28	27
29	26
30	25
31	24
32	47
33	46
34	45
35	44
36	43
37	42
38	41
39	40
40	39
41	38
42	37
43	36
44	35
45	34
46	33
47	32
48	63
49	62
50	61
51	60
52	59
53	58
54	57
55	56
56	55
57	54
58	53
59	52
60	51
61	50
62	49
63	48
64	95
65	94
66	93
67	92
68	91
69	90
70	89
71	88
72	87

n	a(n)
1	1
2	2
3	3
4	5
5	4
6	7
7	6
8	11
9	10
10	9
11	8
12	15
13	14
14	13
15	12
16	23
17	22
18	21
19	20
20	19
21	18
22	17
23	16
24	31
25	30
26	29
27	28
28	27
29	26
30	25
31	24
32	47
33	46
34	45
35	44
36	43
37	42
38	41
39	40
40	39
41	38
42	37
43	36
44	35
45	34
46	33
47	32
48	63
49	62
50	61
51	60
52	59
53	58
54	57
55	56
56	55
57	54
58	53
59	52
60	51
61	50
62	49
63	48
64	95
65	94
66	93
67	92
68	91
69	90
70	89
71	88
72	87

n	a(n)
1	1
2	2
3	3
4	5
5	4
6	7
7	6
8	11
9	10
10	9
11	8
12	15
13	14
14	13
15	12
16	23
17	22
18	21
19	20
20	19
21	18
22	17
23	16
24	31
25	30
26	29
27	28
28	27
29	26
30	25
31	24
32	47
33	46
34	45
35	44
36	43
37	42
38	41
39	40
40	39
41	38
42	37
43	36
44	35
45	34
46	33
47	32
48	63
49	62
50	61
51	60
52	59
53	58
54	57
55	56
56	55
57	54
58	53
59	52
60	51
61	50
62	49
63	48
64	95
65	94
66	93
67	92
68	91
69	90
70	89
71	88
72	87