A257460 - cp's OEIS frontend

A257460 Let b_k=7...7 consist of k>0 7's. Then a(n) is the smallest k such that the concatenation prime(n)b_k is prime, or a(n)=0 if there is no such prime.

n	a(n)
1	2
2	1
3	2
4	0
5	3
6	1
7	2
8	1
9	2
10	48
11	1
12	10
13	2
14	3
15	3
16	3
17	9
18	1
19	1
20	2
21	66
22	1
23	2
24	8
25	1
26	2
27	6
28	3
29	1
30	3
31	1
32	2
33	3
34	6
35	8
36	9
37	7
38	1
39	3
40	2
41	2
42	3
43	17
44	4
45	2
46	1
47	3
48	1
49	2
50	1
51	3
52	2
53	1
54	5
55	17
56	5
57	8
58	16
59	1
60	3
61	1
62	8
63	6
64	2
65	1
66	3
67	3
68	2184
69	6
70	6
71	3
72	2
73	1
74	3
75	1
76	2
77	2
78	4
79	2
80	3
81	3
82	1
83	2
84	1
85	1
86	3
87	6
88	15
89	5
90	1
91	48
92	2
93	1
94	2
95	7
96	2
97	47
98	2
99	1
100	1

[2, 1, 2, 0, 3, 1, 2, 1, 2, 48, 1, 10, 2, 3, 3, 3, 9, 1, 1, 2, 66, 1, 2, 8, 1, 2, 6, 3, 1, 3, 1, 2, 3, 6, 8, 9, 7, 1, 3, 2, 2, 3, 17, 4, 2, 1, 3, 1, 2, 1, 3, 2, 1, 5, 17, 5, 8, 16, 1, 3, 1, 8, 6, 2, 1, 3, 3, 2184, 6, 6, 3, 2, 1, 3, 1, 2, 2, 4, 2, 3, 3, 1, 2, 1, 1, 3, 6, 15, 5, 1, 48, 2, 1, 2, 7, 2, 47, 2, 1, 1]

cp's OEIS Frontend

A257460 Let b_k=7...7 consist of k>0 7's. Then a(n) is the smallest k such that the concatenation prime(n)b_k is prime, or a(n)=0 if there is no such prime.

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List of values