A366918 - cp's OEIS frontend

A366918 a(n) is the number of multiples of n that have exactly n divisors, or -1 if there are infinitely many such numbers.

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

[1, 1, 1, 1, 1, 2, 1, -1, -1, 2, 1, -1, 1, 2, 2, -1, 1, -1, 1, -1, 2, 2, 1, -1, -1, 2, -1, -1, 1, 6, 1, -1, 2, 2, 2, -1, 1, 2, 2, -1, 1, 6, 1, -1, -1, 2, 1, -1, -1, -1, 2, -1, 1, -1, 2, -1, 2, 2, 1, -1, 1, 2, -1, -1, 2, 6, 1, -1, 2, 6, 1, -1, 1, 2, -1, -1, 2, 6, 1, -1, -1, 2, 1, -1, 2, 2, 2, -1, 1, -1, 2, -1, 2, 2, 2]

cp's OEIS Frontend

A366918 a(n) is the number of multiples of n that have exactly n divisors, or -1 if there are infinitely many such numbers.

Table of values

List of values

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

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

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