A077202 - cp's OEIS frontend

A077202 a(1) = 1, a(n) = smallest number such that the concatenation of two successive terms gives a prime which has not occurred earlier.

n	a(n)
1	1
2	1
3	3
4	1
5	7
6	1
7	9
8	7
9	3
10	7
11	9
12	11
13	3
14	11
15	17
16	3
17	13
18	1
19	27
20	1
21	37
22	3
23	17
24	9
25	19
26	1
27	39
28	7
29	19
30	3
31	31
32	19
33	7
34	27
35	7
36	33
37	7
38	39
39	11
40	23
41	3
42	47
43	9
44	29
45	3
46	49
47	1
48	49
49	9
50	37
51	9
52	41
53	9
54	47
55	21
56	1
57	51
58	13
59	19
60	9
61	53
62	23
63	9
64	67
65	3
66	53
67	33
68	13
69	21
70	11
71	29
72	17
73	21
74	13
75	27
76	11
77	51
78	19
79	13
80	61

[1, 1, 3, 1, 7, 1, 9, 7, 3, 7, 9, 11, 3, 11, 17, 3, 13, 1, 27, 1, 37, 3, 17, 9, 19, 1, 39, 7, 19, 3, 31, 19, 7, 27, 7, 33, 7, 39, 11, 23, 3, 47, 9, 29, 3, 49, 1, 49, 9, 37, 9, 41, 9, 47, 21, 1, 51, 13, 19, 9, 53, 23, 9, 67, 3, 53, 33, 13, 21, 11, 29, 17, 21, 13, 27, 11, 51, 19, 13, 61]

cp's OEIS Frontend

A077202 a(1) = 1, a(n) = smallest number such that the concatenation of two successive terms gives a prime which has not occurred earlier.

Table of values

List of values

n	a(n)
1	1
2	1
3	3
4	1
5	7
6	1
7	9
8	7
9	3
10	7
11	9
12	11
13	3
14	11
15	17
16	3
17	13
18	1
19	27
20	1
21	37
22	3
23	17
24	9
25	19
26	1
27	39
28	7
29	19
30	3
31	31
32	19
33	7
34	27
35	7
36	33
37	7
38	39
39	11
40	23
41	3
42	47
43	9
44	29
45	3
46	49
47	1
48	49
49	9
50	37
51	9
52	41
53	9
54	47
55	21
56	1
57	51
58	13
59	19
60	9
61	53
62	23
63	9
64	67
65	3
66	53
67	33
68	13
69	21
70	11
71	29
72	17
73	21
74	13
75	27
76	11
77	51
78	19
79	13
80	61

n	a(n)
1	1
2	1
3	3
4	1
5	7
6	1
7	9
8	7
9	3
10	7
11	9
12	11
13	3
14	11
15	17
16	3
17	13
18	1
19	27
20	1
21	37
22	3
23	17
24	9
25	19
26	1
27	39
28	7
29	19
30	3
31	31
32	19
33	7
34	27
35	7
36	33
37	7
38	39
39	11
40	23
41	3
42	47
43	9
44	29
45	3
46	49
47	1
48	49
49	9
50	37
51	9
52	41
53	9
54	47
55	21
56	1
57	51
58	13
59	19
60	9
61	53
62	23
63	9
64	67
65	3
66	53
67	33
68	13
69	21
70	11
71	29
72	17
73	21
74	13
75	27
76	11
77	51
78	19
79	13
80	61

n	a(n)
1	1
2	1
3	3
4	1
5	7
6	1
7	9
8	7
9	3
10	7
11	9
12	11
13	3
14	11
15	17
16	3
17	13
18	1
19	27
20	1
21	37
22	3
23	17
24	9
25	19
26	1
27	39
28	7
29	19
30	3
31	31
32	19
33	7
34	27
35	7
36	33
37	7
38	39
39	11
40	23
41	3
42	47
43	9
44	29
45	3
46	49
47	1
48	49
49	9
50	37
51	9
52	41
53	9
54	47
55	21
56	1
57	51
58	13
59	19
60	9
61	53
62	23
63	9
64	67
65	3
66	53
67	33
68	13
69	21
70	11
71	29
72	17
73	21
74	13
75	27
76	11
77	51
78	19
79	13
80	61