A154723 - cp's OEIS frontend

A154723 Triangle read by rows in which row n lists all the pairs of noncomposite numbers that are equidistant from n, or only n if there are no such pairs, as shown below in the example.

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

[1, 1, 3, 1, 5, 1, 3, 5, 7, 3, 7, 1, 5, 7, 11, 1, 3, 11, 13, 3, 5, 11, 13, 1, 5, 7, 11, 13, 17, 1, 3, 7, 13, 17, 19, 3, 5, 17, 19, 1, 5, 7, 11, 13, 17, 19, 23, 3, 7, 19, 23, 5, 11, 17, 23, 1, 7, 11, 13, 17, 19, 23, 29, 1, 3, 13, 19, 29, 31, 3]

cp's OEIS Frontend

A154723 Triangle read by rows in which row n lists all the pairs of noncomposite numbers that are equidistant from n, or only n if there are no such pairs, as shown below in the example.

Table of values

List of values

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

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

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