A128280 - cp's OEIS frontend

A128280 a(n) is the least number not occurring earlier such that a(n)+a(n-1) is prime, a(0) = 0.

n	a(n)
0	0
1	2
2	1
3	4
4	3
5	8
6	5
7	6
8	7
9	10
10	9
11	14
12	15
13	16
14	13
15	18
16	11
17	12
18	17
19	20
20	21
21	22
22	19
23	24
24	23
25	30
26	29
27	32
28	27
29	26
30	33
31	28
32	25
33	34
34	37
35	36
36	31
37	40
38	39
39	44
40	35
41	38
42	41
43	42
44	47
45	50
46	51
47	46
48	43
49	54
50	49
51	48
52	53
53	56
54	45
55	52
56	55
57	58
58	69
59	62
60	65
61	66
62	61
63	70
64	57
65	74
66	63
67	64
68	67
69	60
70	71
71	68
72	59

[0, 2, 1, 4, 3, 8, 5, 6, 7, 10, 9, 14, 15, 16, 13, 18, 11, 12, 17, 20, 21, 22, 19, 24, 23, 30, 29, 32, 27, 26, 33, 28, 25, 34, 37, 36, 31, 40, 39, 44, 35, 38, 41, 42, 47, 50, 51, 46, 43, 54, 49, 48, 53, 56, 45, 52, 55, 58, 69, 62, 65, 66, 61, 70, 57, 74, 63, 64, 67, 60, 71, 68, 59]

cp's OEIS Frontend

A128280 a(n) is the least number not occurring earlier such that a(n)+a(n-1) is prime, a(0) = 0.

Table of values

List of values

n	a(n)
0	0
1	2
2	1
3	4
4	3
5	8
6	5
7	6
8	7
9	10
10	9
11	14
12	15
13	16
14	13
15	18
16	11
17	12
18	17
19	20
20	21
21	22
22	19
23	24
24	23
25	30
26	29
27	32
28	27
29	26
30	33
31	28
32	25
33	34
34	37
35	36
36	31
37	40
38	39
39	44
40	35
41	38
42	41
43	42
44	47
45	50
46	51
47	46
48	43
49	54
50	49
51	48
52	53
53	56
54	45
55	52
56	55
57	58
58	69
59	62
60	65
61	66
62	61
63	70
64	57
65	74
66	63
67	64
68	67
69	60
70	71
71	68
72	59

n	a(n)
0	0
1	2
2	1
3	4
4	3
5	8
6	5
7	6
8	7
9	10
10	9
11	14
12	15
13	16
14	13
15	18
16	11
17	12
18	17
19	20
20	21
21	22
22	19
23	24
24	23
25	30
26	29
27	32
28	27
29	26
30	33
31	28
32	25
33	34
34	37
35	36
36	31
37	40
38	39
39	44
40	35
41	38
42	41
43	42
44	47
45	50
46	51
47	46
48	43
49	54
50	49
51	48
52	53
53	56
54	45
55	52
56	55
57	58
58	69
59	62
60	65
61	66
62	61
63	70
64	57
65	74
66	63
67	64
68	67
69	60
70	71
71	68
72	59

n	a(n)
0	0
1	2
2	1
3	4
4	3
5	8
6	5
7	6
8	7
9	10
10	9
11	14
12	15
13	16
14	13
15	18
16	11
17	12
18	17
19	20
20	21
21	22
22	19
23	24
24	23
25	30
26	29
27	32
28	27
29	26
30	33
31	28
32	25
33	34
34	37
35	36
36	31
37	40
38	39
39	44
40	35
41	38
42	41
43	42
44	47
45	50
46	51
47	46
48	43
49	54
50	49
51	48
52	53
53	56
54	45
55	52
56	55
57	58
58	69
59	62
60	65
61	66
62	61
63	70
64	57
65	74
66	63
67	64
68	67
69	60
70	71
71	68
72	59