A213790 - cp's OEIS frontend

A213790 Least number k such that 10^(n+k) - 10^n - 1 is prime.

n	a(n)
1	1
2	10
3	1
4	2
5	2
6	3
7	1
8	6
9	2
10	20
11	3
12	4
13	30
14	9
15	4
16	5
17	14
18	4
19	1
20	658
21	6
22	10
23	32
24	9
25	2
26	9
27	109
28	8
29	1
30	7
31	12
32	6
33	4
34	2
35	5
36	137
37	1
38	15
39	112
40	30
41	237
42	83
43	12
44	21
45	5
46	4
47	20
48	15
49	42
50	3
51	16
52	41
53	26
54	60
55	157
56	8
57	16
58	76
59	69
60	10
61	4
62	4
63	120
64	39
65	8
66	7
67	115
68	22
69	14
70	2
71	102

[1, 10, 1, 2, 2, 3, 1, 6, 2, 20, 3, 4, 30, 9, 4, 5, 14, 4, 1, 658, 6, 10, 32, 9, 2, 9, 109, 8, 1, 7, 12, 6, 4, 2, 5, 137, 1, 15, 112, 30, 237, 83, 12, 21, 5, 4, 20, 15, 42, 3, 16, 41, 26, 60, 157, 8, 16, 76, 69, 10, 4, 4, 120, 39, 8, 7, 115, 22, 14, 2, 102]

cp's OEIS Frontend

A213790 Least number k such that 10^(n+k) - 10^n - 1 is prime.

Table of values

List of values

n	a(n)
1	1
2	10
3	1
4	2
5	2
6	3
7	1
8	6
9	2
10	20
11	3
12	4
13	30
14	9
15	4
16	5
17	14
18	4
19	1
20	658
21	6
22	10
23	32
24	9
25	2
26	9
27	109
28	8
29	1
30	7
31	12
32	6
33	4
34	2
35	5
36	137
37	1
38	15
39	112
40	30
41	237
42	83
43	12
44	21
45	5
46	4
47	20
48	15
49	42
50	3
51	16
52	41
53	26
54	60
55	157
56	8
57	16
58	76
59	69
60	10
61	4
62	4
63	120
64	39
65	8
66	7
67	115
68	22
69	14
70	2
71	102

n	a(n)
1	1
2	10
3	1
4	2
5	2
6	3
7	1
8	6
9	2
10	20
11	3
12	4
13	30
14	9
15	4
16	5
17	14
18	4
19	1
20	658
21	6
22	10
23	32
24	9
25	2
26	9
27	109
28	8
29	1
30	7
31	12
32	6
33	4
34	2
35	5
36	137
37	1
38	15
39	112
40	30
41	237
42	83
43	12
44	21
45	5
46	4
47	20
48	15
49	42
50	3
51	16
52	41
53	26
54	60
55	157
56	8
57	16
58	76
59	69
60	10
61	4
62	4
63	120
64	39
65	8
66	7
67	115
68	22
69	14
70	2
71	102

n	a(n)
1	1
2	10
3	1
4	2
5	2
6	3
7	1
8	6
9	2
10	20
11	3
12	4
13	30
14	9
15	4
16	5
17	14
18	4
19	1
20	658
21	6
22	10
23	32
24	9
25	2
26	9
27	109
28	8
29	1
30	7
31	12
32	6
33	4
34	2
35	5
36	137
37	1
38	15
39	112
40	30
41	237
42	83
43	12
44	21
45	5
46	4
47	20
48	15
49	42
50	3
51	16
52	41
53	26
54	60
55	157
56	8
57	16
58	76
59	69
60	10
61	4
62	4
63	120
64	39
65	8
66	7
67	115
68	22
69	14
70	2
71	102