A243374 - cp's OEIS frontend

A243374 Least number k such that n//k and k//n are both prime where // is the concatenation function, or 0 if no such k exists.

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

[1, 0, 1, 0, 0, 0, 1, 0, 7, 0, 3, 0, 1, 0, 0, 0, 3, 0, 7, 0, 13, 0, 11, 0, 0, 0, 1, 0, 27, 0, 1, 0, 7, 0, 0, 0, 3, 0, 7, 0, 9, 0, 39, 0, 0, 0, 9, 0, 1, 0, 19, 0, 51, 0, 0, 0, 1, 0, 3, 0, 7, 0, 1, 0, 0, 0, 3, 0, 49, 0, 9, 0, 3, 0, 0, 0, 17, 0, 19, 0, 1, 0, 9, 0, 0, 0, 7, 0, 23]

cp's OEIS Frontend

A243374 Least number k such that n//k and k//n are both prime where // is the concatenation function, or 0 if no such k exists.

Table of values

List of values

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

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

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