A241472 - cp's OEIS frontend

A241472 a(n) = |{0 < k < sqrt(prime(n)): k^2 + 1 is a quadratic residue modulo prime(n)}|.

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

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

cp's OEIS Frontend

A241472 a(n) = |{0 < k < sqrt(prime(n)): k^2 + 1 is a quadratic residue modulo prime(n)}|.

Table of values

List of values

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

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

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