A189827 - cp's OEIS frontend

A189827 a(n) = d(n-1) + d(n+1), where d(k) is the number of divisors of k.

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

[3, 5, 4, 7, 4, 8, 5, 8, 5, 10, 4, 10, 6, 9, 6, 11, 4, 12, 6, 10, 6, 12, 5, 12, 7, 10, 6, 14, 4, 14, 6, 10, 8, 13, 6, 13, 6, 12, 6, 16, 4, 14, 8, 10, 8, 14, 5, 16, 7, 12, 6, 14, 6, 16, 8, 12, 6, 16, 4, 16, 8, 11, 10, 15, 6, 14, 6, 14, 6, 20, 4, 16, 8, 10, 10]

cp's OEIS Frontend

A189827 a(n) = d(n-1) + d(n+1), where d(k) is the number of divisors of k.

Table of values

List of values

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

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

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