A231122 - cp's OEIS frontend

A231122 Numbers k >= 0 such that 2^k is number of ways to write n as n = x*y, where x, y = squarefree numbers, 1 <= x <= n, 1 <= y <= n, or -1 if no such k exists.

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

[0, 0, 0, 0, 0, 1, 0, -1, 0, 1, 0, 0, 0, 1, 1, -1, 0, 0, 0, 0, 1, 1, 0, -1, 0, 1, -1, 0, 0, 2, 0, -1, 1, 1, 1, 0, 0, 1, 1, -1, 0, 2, 0, 0, 0, 1, 0, -1, 0, 0, 1, 0, 0, -1, 1, -1, 1, 1, 0, 1, 0, 1, 0, -1, 1, 2, 0, 0, 1, 2, 0, -1, 0, 1, 0, 0, 1, 2, 0, -1, -1, 1, 0, 1, 1]

cp's OEIS Frontend

A231122 Numbers k >= 0 such that 2^k is number of ways to write n as n = x*y, where x, y = squarefree numbers, 1 <= x <= n, 1 <= y <= n, or -1 if no such k exists.

Table of values

List of values

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

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

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