A133949 - cp's OEIS frontend

A133949 a(n) = the number of "non-isolated divisors" of n(n+1)/2. A positive divisor k of n is non-isolated if either k-1 or k+1 also divides n.

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

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

cp's OEIS Frontend

A133949 a(n) = the number of "non-isolated divisors" of n(n+1)/2. A positive divisor k of n is non-isolated if either k-1 or k+1 also divides n.

Table of values

List of values

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

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

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