A133947 - cp's OEIS frontend

A133947 a(n) = the number of "non-isolated divisors" of n(n+1). A positive divisor, k, of n is non-isolated if (k-1) or (k+1) also divides n.

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

[2, 3, 4, 4, 5, 5, 4, 6, 7, 4, 6, 6, 4, 8, 8, 4, 5, 5, 6, 11, 7, 4, 6, 8, 4, 5, 8, 4, 7, 7, 4, 8, 5, 4, 15, 6, 4, 5, 10, 6, 7, 7, 4, 12, 9, 4, 6, 9, 4, 7, 8, 4, 5, 10, 10, 9, 5, 4, 8, 8, 4, 7, 10, 6, 9, 5, 4, 6, 10, 4, 8, 8, 4, 7, 10, 4, 11, 5, 6, 13, 5, 4, 8, 15, 4, 5, 8, 4, 9, 13, 6, 6, 5, 4, 12, 6, 4, 9]

cp's OEIS Frontend

A133947 a(n) = the number of "non-isolated divisors" of n(n+1). A positive divisor, k, of n is non-isolated if (k-1) or (k+1) also divides n.

Table of values

List of values

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

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

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