A255920 - cp's OEIS frontend

A255920 Number of primes p with p < n such that n^(p-1) == 1 (mod p^2) i.e., number of Wieferich primes to base n less than n.

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

[0, 0, 0, 1, 0, 1, 1, 1, 1, 0, 0, 1, 0, 0, 0, 2, 2, 3, 0, 1, 1, 1, 1, 1, 2, 1, 3, 1, 1, 1, 1, 1, 0, 1, 0, 2, 1, 0, 2, 2, 1, 1, 1, 1, 1, 0, 1, 2, 1, 2, 0, 3, 1, 1, 0, 2, 0, 0, 1, 1, 2, 2, 1, 2, 0, 2, 3, 2, 1, 2, 0, 2, 1, 2, 2, 1, 1, 1, 3, 2, 2, 0, 0, 1, 0, 0, 0]

cp's OEIS Frontend

A255920 Number of primes p with p < n such that n^(p-1) == 1 (mod p^2) i.e., number of Wieferich primes to base n less than n.

Table of values

List of values

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

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

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