A247339 - cp's OEIS frontend

A247339 a(n) is the least number k such that the greatest prime divisor of k^2+1 is the smallest prime divisor of n^2+1.

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

[1, 2, 1, 4, 1, 6, 1, 2, 1, 10, 1, 2, 1, 14, 1, 16, 1, 2, 1, 20, 1, 2, 1, 24, 1, 26, 1, 2, 1, 4, 1, 2, 1, 5, 1, 36, 1, 2, 1, 40, 1, 2, 1, 5, 1, 12, 1, 2, 1, 9, 1, 2, 1, 54, 1, 56, 1, 2, 1, 5, 1, 2, 1, 4, 1, 66, 1, 2, 1, 5, 1, 2, 1, 74, 1, 23, 1, 2, 1, 6, 1, 2]

cp's OEIS Frontend

A247339 a(n) is the least number k such that the greatest prime divisor of k^2+1 is the smallest prime divisor of n^2+1.

Table of values

List of values

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

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

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