A051686 - cp's OEIS frontend

A051686 Smallest prime p such that 2n*p+1 is also prime.

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

[2, 3, 2, 2, 3, 3, 2, 7, 2, 2, 3, 3, 2, 7, 2, 3, 3, 2, 5, 7, 3, 2, 3, 2, 2, 3, 2, 2, 19, 3, 5, 3, 3, 2, 3, 13, 2, 3, 2, 3, 19, 5, 2, 7, 2, 3, 3, 2, 2, 7, 3, 3, 7, 5, 3, 3, 2, 2, 7, 2, 3, 3, 3, 2, 7, 3, 2, 3, 2, 2, 13, 3, 2, 37, 5, 3, 3, 2, 2, 13, 3, 5, 3, 2, 11, 13, 2, 2, 31, 3, 3, 7, 2, 5, 3, 3, 2, 7, 2, 2]

cp's OEIS Frontend

A051686 Smallest prime p such that 2n*p+1 is also prime.

Table of values

List of values

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

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

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