A316776 - cp's OEIS frontend

A316776 a(n) is the number of integers 0 < k < n such that n^2 - k^2 is a semiprime.

n	a(n)
1	0
2	0
3	0
4	1
5	2
6	1
7	1
8	3
9	2
10	2
11	3
12	3
13	3
14	2
15	3
16	2
17	4
18	5
19	1
20	4
21	4
22	3
23	3
24	5
25	5
26	4
27	5
28	4
29	4
30	6
31	2
32	5
33	7
34	2
35	6
36	6
37	4
38	5
39	8
40	4
41	4
42	8
43	5
44	5
45	9
46	5
47	5
48	8
49	3
50	6
51	8
52	5
53	5
54	8
55	6
56	8
57	10
58	7
59	5
60	13
61	4
62	6
63	10
64	3
65	8
66	9
67	6
68	5
69	8
70	7
71	8
72	12
73	6
74	5
75	12
76	4
77	8
78	12
79	4
80	9
81	11
82	5
83	5
84	13
85	10
86	6
87	11
88	7
89	7
90	14
91	6
92	9
93	14
94	6
95	8
96	11

[0, 0, 0, 1, 2, 1, 1, 3, 2, 2, 3, 3, 3, 2, 3, 2, 4, 5, 1, 4, 4, 3, 3, 5, 5, 4, 5, 4, 4, 6, 2, 5, 7, 2, 6, 6, 4, 5, 8, 4, 4, 8, 5, 5, 9, 5, 5, 8, 3, 6, 8, 5, 5, 8, 6, 8, 10, 7, 5, 13, 4, 6, 10, 3, 8, 9, 6, 5, 8, 7, 8, 12, 6, 5, 12, 4, 8, 12, 4, 9, 11, 5, 5, 13, 10, 6, 11, 7, 7, 14, 6, 9, 14, 6, 8, 11]

cp's OEIS Frontend

A316776 a(n) is the number of integers 0 < k < n such that n^2 - k^2 is a semiprime.

Table of values

List of values

n	a(n)
1	0
2	0
3	0
4	1
5	2
6	1
7	1
8	3
9	2
10	2
11	3
12	3
13	3
14	2
15	3
16	2
17	4
18	5
19	1
20	4
21	4
22	3
23	3
24	5
25	5
26	4
27	5
28	4
29	4
30	6
31	2
32	5
33	7
34	2
35	6
36	6
37	4
38	5
39	8
40	4
41	4
42	8
43	5
44	5
45	9
46	5
47	5
48	8
49	3
50	6
51	8
52	5
53	5
54	8
55	6
56	8
57	10
58	7
59	5
60	13
61	4
62	6
63	10
64	3
65	8
66	9
67	6
68	5
69	8
70	7
71	8
72	12
73	6
74	5
75	12
76	4
77	8
78	12
79	4
80	9
81	11
82	5
83	5
84	13
85	10
86	6
87	11
88	7
89	7
90	14
91	6
92	9
93	14
94	6
95	8
96	11

n	a(n)
1	0
2	0
3	0
4	1
5	2
6	1
7	1
8	3
9	2
10	2
11	3
12	3
13	3
14	2
15	3
16	2
17	4
18	5
19	1
20	4
21	4
22	3
23	3
24	5
25	5
26	4
27	5
28	4
29	4
30	6
31	2
32	5
33	7
34	2
35	6
36	6
37	4
38	5
39	8
40	4
41	4
42	8
43	5
44	5
45	9
46	5
47	5
48	8
49	3
50	6
51	8
52	5
53	5
54	8
55	6
56	8
57	10
58	7
59	5
60	13
61	4
62	6
63	10
64	3
65	8
66	9
67	6
68	5
69	8
70	7
71	8
72	12
73	6
74	5
75	12
76	4
77	8
78	12
79	4
80	9
81	11
82	5
83	5
84	13
85	10
86	6
87	11
88	7
89	7
90	14
91	6
92	9
93	14
94	6
95	8
96	11

n	a(n)
1	0
2	0
3	0
4	1
5	2
6	1
7	1
8	3
9	2
10	2
11	3
12	3
13	3
14	2
15	3
16	2
17	4
18	5
19	1
20	4
21	4
22	3
23	3
24	5
25	5
26	4
27	5
28	4
29	4
30	6
31	2
32	5
33	7
34	2
35	6
36	6
37	4
38	5
39	8
40	4
41	4
42	8
43	5
44	5
45	9
46	5
47	5
48	8
49	3
50	6
51	8
52	5
53	5
54	8
55	6
56	8
57	10
58	7
59	5
60	13
61	4
62	6
63	10
64	3
65	8
66	9
67	6
68	5
69	8
70	7
71	8
72	12
73	6
74	5
75	12
76	4
77	8
78	12
79	4
80	9
81	11
82	5
83	5
84	13
85	10
86	6
87	11
88	7
89	7
90	14
91	6
92	9
93	14
94	6
95	8
96	11