A308598 - cp's OEIS frontend

A308598 The smaller term of the pair (a(n), a(n+1)) is always prime and in each pair there is a composite number; a(1) = 2 and the sequence is always extended with the smallest integer not yet present and not leading to a contradiction.

n	a(n)
1	2
2	4
3	3
4	6
5	5
6	8
7	7
8	12
9	11
10	14
11	13
12	18
13	17
14	20
15	19
16	24
17	23
18	30
19	29
20	32
21	31
22	38
23	37
24	42
25	41
26	44
27	43
28	48
29	47
30	54
31	53
32	60
33	59
34	62
35	61
36	68
37	67
38	72
39	71
40	74
41	73
42	80
43	79
44	84
45	83
46	90
47	89
48	98
49	97
50	102
51	101
52	104
53	103
54	108
55	107
56	110
57	109
58	114
59	113
60	128
61	127
62	132
63	131
64	138
65	137
66	140
67	139
68	150
69	149

[2, 4, 3, 6, 5, 8, 7, 12, 11, 14, 13, 18, 17, 20, 19, 24, 23, 30, 29, 32, 31, 38, 37, 42, 41, 44, 43, 48, 47, 54, 53, 60, 59, 62, 61, 68, 67, 72, 71, 74, 73, 80, 79, 84, 83, 90, 89, 98, 97, 102, 101, 104, 103, 108, 107, 110, 109, 114, 113, 128, 127, 132, 131, 138, 137, 140, 139, 150, 149]

cp's OEIS Frontend

A308598 The smaller term of the pair (a(n), a(n+1)) is always prime and in each pair there is a composite number; a(1) = 2 and the sequence is always extended with the smallest integer not yet present and not leading to a contradiction.

Table of values

List of values

n	a(n)
1	2
2	4
3	3
4	6
5	5
6	8
7	7
8	12
9	11
10	14
11	13
12	18
13	17
14	20
15	19
16	24
17	23
18	30
19	29
20	32
21	31
22	38
23	37
24	42
25	41
26	44
27	43
28	48
29	47
30	54
31	53
32	60
33	59
34	62
35	61
36	68
37	67
38	72
39	71
40	74
41	73
42	80
43	79
44	84
45	83
46	90
47	89
48	98
49	97
50	102
51	101
52	104
53	103
54	108
55	107
56	110
57	109
58	114
59	113
60	128
61	127
62	132
63	131
64	138
65	137
66	140
67	139
68	150
69	149

n	a(n)
1	2
2	4
3	3
4	6
5	5
6	8
7	7
8	12
9	11
10	14
11	13
12	18
13	17
14	20
15	19
16	24
17	23
18	30
19	29
20	32
21	31
22	38
23	37
24	42
25	41
26	44
27	43
28	48
29	47
30	54
31	53
32	60
33	59
34	62
35	61
36	68
37	67
38	72
39	71
40	74
41	73
42	80
43	79
44	84
45	83
46	90
47	89
48	98
49	97
50	102
51	101
52	104
53	103
54	108
55	107
56	110
57	109
58	114
59	113
60	128
61	127
62	132
63	131
64	138
65	137
66	140
67	139
68	150
69	149

n	a(n)
1	2
2	4
3	3
4	6
5	5
6	8
7	7
8	12
9	11
10	14
11	13
12	18
13	17
14	20
15	19
16	24
17	23
18	30
19	29
20	32
21	31
22	38
23	37
24	42
25	41
26	44
27	43
28	48
29	47
30	54
31	53
32	60
33	59
34	62
35	61
36	68
37	67
38	72
39	71
40	74
41	73
42	80
43	79
44	84
45	83
46	90
47	89
48	98
49	97
50	102
51	101
52	104
53	103
54	108
55	107
56	110
57	109
58	114
59	113
60	128
61	127
62	132
63	131
64	138
65	137
66	140
67	139
68	150
69	149