A307118 - cp's OEIS frontend

A307118 a(1) = 0; for n>1, a(n) = dr(n-1) + dr(n) + dr(n+1), where dr(n) is the number of nontrivial divisors of n (A070824).

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

[0, 0, 1, 1, 3, 2, 4, 3, 5, 3, 6, 4, 6, 4, 7, 5, 7, 4, 8, 6, 8, 4, 8, 7, 9, 5, 8, 6, 10, 6, 10, 6, 8, 6, 11, 9, 9, 4, 10, 8, 12, 6, 10, 8, 10, 6, 10, 9, 13, 7, 10, 6, 10, 8, 14, 10, 10, 4, 12, 10, 12, 6, 11, 11, 13, 8, 10, 6, 12, 8, 16, 10, 12, 6, 10, 10, 12, 8, 14, 11, 13, 5, 12, 12, 14, 6, 10, 8, 16, 12, 16]

cp's OEIS Frontend

A307118 a(1) = 0; for n>1, a(n) = dr(n-1) + dr(n) + dr(n+1), where dr(n) is the number of nontrivial divisors of n (A070824).

Table of values

List of values

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

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

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