A305426 - cp's OEIS frontend

A305426 Number of proper divisors of n of the form 2^k - 1 for k >= 1.

n	a(n)
1	0
2	1
3	1
4	1
5	1
6	2
7	1
8	1
9	2
10	1
11	1
12	2
13	1
14	2
15	2
16	1
17	1
18	2
19	1
20	1
21	3
22	1
23	1
24	2
25	1
26	1
27	2
28	2
29	1
30	3
31	1
32	1
33	2
34	1
35	2
36	2
37	1
38	1
39	2
40	1
41	1
42	3
43	1
44	1
45	3
46	1
47	1
48	2
49	2
50	1
51	2
52	1
53	1
54	2
55	1
56	2
57	2
58	1
59	1
60	3
61	1
62	2
63	3
64	1
65	1
66	2
67	1
68	1
69	2
70	2
71	1
72	2
73	1
74	1
75	3
76	1
77	2
78	2
79	1
80	1
81	2
82	1
83	1
84	3
85	1
86	1
87	2
88	1
89	1
90	3
91	2
92	1
93	3
94	1
95	1
96	2
97	1
98	2
99	2
100	1
101	1
102	2
103	1
104	1
105	4

[0, 1, 1, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 2, 2, 1, 1, 2, 1, 1, 3, 1, 1, 2, 1, 1, 2, 2, 1, 3, 1, 1, 2, 1, 2, 2, 1, 1, 2, 1, 1, 3, 1, 1, 3, 1, 1, 2, 2, 1, 2, 1, 1, 2, 1, 2, 2, 1, 1, 3, 1, 2, 3, 1, 1, 2, 1, 1, 2, 2, 1, 2, 1, 1, 3, 1, 2, 2, 1, 1, 2, 1, 1, 3, 1, 1, 2, 1, 1, 3, 2, 1, 3, 1, 1, 2, 1, 2, 2, 1, 1, 2, 1, 1, 4]

cp's OEIS Frontend

A305426 Number of proper divisors of n of the form 2^k - 1 for k >= 1.

Table of values

List of values

n	a(n)
1	0
2	1
3	1
4	1
5	1
6	2
7	1
8	1
9	2
10	1
11	1
12	2
13	1
14	2
15	2
16	1
17	1
18	2
19	1
20	1
21	3
22	1
23	1
24	2
25	1
26	1
27	2
28	2
29	1
30	3
31	1
32	1
33	2
34	1
35	2
36	2
37	1
38	1
39	2
40	1
41	1
42	3
43	1
44	1
45	3
46	1
47	1
48	2
49	2
50	1
51	2
52	1
53	1
54	2
55	1
56	2
57	2
58	1
59	1
60	3
61	1
62	2
63	3
64	1
65	1
66	2
67	1
68	1
69	2
70	2
71	1
72	2
73	1
74	1
75	3
76	1
77	2
78	2
79	1
80	1
81	2
82	1
83	1
84	3
85	1
86	1
87	2
88	1
89	1
90	3
91	2
92	1
93	3
94	1
95	1
96	2
97	1
98	2
99	2
100	1
101	1
102	2
103	1
104	1
105	4

n	a(n)
1	0
2	1
3	1
4	1
5	1
6	2
7	1
8	1
9	2
10	1
11	1
12	2
13	1
14	2
15	2
16	1
17	1
18	2
19	1
20	1
21	3
22	1
23	1
24	2
25	1
26	1
27	2
28	2
29	1
30	3
31	1
32	1
33	2
34	1
35	2
36	2
37	1
38	1
39	2
40	1
41	1
42	3
43	1
44	1
45	3
46	1
47	1
48	2
49	2
50	1
51	2
52	1
53	1
54	2
55	1
56	2
57	2
58	1
59	1
60	3
61	1
62	2
63	3
64	1
65	1
66	2
67	1
68	1
69	2
70	2
71	1
72	2
73	1
74	1
75	3
76	1
77	2
78	2
79	1
80	1
81	2
82	1
83	1
84	3
85	1
86	1
87	2
88	1
89	1
90	3
91	2
92	1
93	3
94	1
95	1
96	2
97	1
98	2
99	2
100	1
101	1
102	2
103	1
104	1
105	4

n	a(n)
1	0
2	1
3	1
4	1
5	1
6	2
7	1
8	1
9	2
10	1
11	1
12	2
13	1
14	2
15	2
16	1
17	1
18	2
19	1
20	1
21	3
22	1
23	1
24	2
25	1
26	1
27	2
28	2
29	1
30	3
31	1
32	1
33	2
34	1
35	2
36	2
37	1
38	1
39	2
40	1
41	1
42	3
43	1
44	1
45	3
46	1
47	1
48	2
49	2
50	1
51	2
52	1
53	1
54	2
55	1
56	2
57	2
58	1
59	1
60	3
61	1
62	2
63	3
64	1
65	1
66	2
67	1
68	1
69	2
70	2
71	1
72	2
73	1
74	1
75	3
76	1
77	2
78	2
79	1
80	1
81	2
82	1
83	1
84	3
85	1
86	1
87	2
88	1
89	1
90	3
91	2
92	1
93	3
94	1
95	1
96	2
97	1
98	2
99	2
100	1
101	1
102	2
103	1
104	1
105	4