A120223 - cp's OEIS frontend

A120223 a(n) is the minimal number k>1 such that n+k and n*k+1 are primes.

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

[2, 3, 2, 3, 2, 5, 4, 5, 2, 3, 2, 5, 4, 3, 2, 7, 6, 11, 10, 3, 2, 9, 6, 13, 4, 3, 4, 15, 2, 7, 10, 11, 10, 3, 2, 5, 4, 5, 2, 7, 2, 5, 4, 9, 14, 13, 6, 5, 4, 3, 2, 21, 14, 5, 6, 5, 4, 9, 12, 7, 6, 5, 10, 3, 2, 5, 4, 15, 2, 3, 8, 25, 6, 27, 8, 3, 6, 11, 4, 3, 2, 15, 6, 5, 12, 11, 20, 15, 12, 7, 6, 5, 4, 3]

cp's OEIS Frontend

A120223 a(n) is the minimal number k>1 such that n+k and n*k+1 are primes.

Table of values

List of values

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

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

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