A094045 - cp's OEIS frontend

A094045 Alternate composite and prime numbers not included earlier such that every concatenation of a pair of terms is a prime: a(2n) is prime and a(2n-1) is nonprime.

n	a(n)
1	1
2	3
3	49
4	19
5	9
6	7
7	27
8	11
9	51
10	13
11	21
12	29
13	39
14	17
15	33
16	23
17	57
18	37
19	69
20	47
21	87
22	31
23	63
24	43
25	91
26	61
27	99
28	41
29	77
30	53
31	81
32	67
33	93
34	71
35	119
36	59
37	123
38	73
39	121
40	97
41	117
42	79
43	111
44	103
45	141
46	101
47	159
48	113
49	143
50	89
51	153
52	83
53	177
54	109
55	133
56	157
57	189
58	127
59	207
60	139
61	169
62	151
63	171
64	131

[1, 3, 49, 19, 9, 7, 27, 11, 51, 13, 21, 29, 39, 17, 33, 23, 57, 37, 69, 47, 87, 31, 63, 43, 91, 61, 99, 41, 77, 53, 81, 67, 93, 71, 119, 59, 123, 73, 121, 97, 117, 79, 111, 103, 141, 101, 159, 113, 143, 89, 153, 83, 177, 109, 133, 157, 189, 127, 207, 139, 169, 151, 171, 131]

cp's OEIS Frontend

A094045 Alternate composite and prime numbers not included earlier such that every concatenation of a pair of terms is a prime: a(2n) is prime and a(2n-1) is nonprime.

Table of values

List of values

n	a(n)
1	1
2	3
3	49
4	19
5	9
6	7
7	27
8	11
9	51
10	13
11	21
12	29
13	39
14	17
15	33
16	23
17	57
18	37
19	69
20	47
21	87
22	31
23	63
24	43
25	91
26	61
27	99
28	41
29	77
30	53
31	81
32	67
33	93
34	71
35	119
36	59
37	123
38	73
39	121
40	97
41	117
42	79
43	111
44	103
45	141
46	101
47	159
48	113
49	143
50	89
51	153
52	83
53	177
54	109
55	133
56	157
57	189
58	127
59	207
60	139
61	169
62	151
63	171
64	131

n	a(n)
1	1
2	3
3	49
4	19
5	9
6	7
7	27
8	11
9	51
10	13
11	21
12	29
13	39
14	17
15	33
16	23
17	57
18	37
19	69
20	47
21	87
22	31
23	63
24	43
25	91
26	61
27	99
28	41
29	77
30	53
31	81
32	67
33	93
34	71
35	119
36	59
37	123
38	73
39	121
40	97
41	117
42	79
43	111
44	103
45	141
46	101
47	159
48	113
49	143
50	89
51	153
52	83
53	177
54	109
55	133
56	157
57	189
58	127
59	207
60	139
61	169
62	151
63	171
64	131

n	a(n)
1	1
2	3
3	49
4	19
5	9
6	7
7	27
8	11
9	51
10	13
11	21
12	29
13	39
14	17
15	33
16	23
17	57
18	37
19	69
20	47
21	87
22	31
23	63
24	43
25	91
26	61
27	99
28	41
29	77
30	53
31	81
32	67
33	93
34	71
35	119
36	59
37	123
38	73
39	121
40	97
41	117
42	79
43	111
44	103
45	141
46	101
47	159
48	113
49	143
50	89
51	153
52	83
53	177
54	109
55	133
56	157
57	189
58	127
59	207
60	139
61	169
62	151
63	171
64	131