A318768 - cp's OEIS frontend

A318768 a(n) = Sum_{d|n} (-1)^(n/d+1) * Sum_{j|d} tau(j), where tau = number of divisors (A000005).

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

[1, 2, 4, 2, 4, 8, 4, 0, 10, 8, 4, 8, 4, 8, 16, -5, 4, 20, 4, 8, 16, 8, 4, 0, 10, 8, 20, 8, 4, 32, 4, -14, 16, 8, 16, 20, 4, 8, 16, 0, 4, 32, 4, 8, 40, 8, 4, -20, 10, 20, 16, 8, 4, 40, 16, 0, 16, 8, 4, 32, 4, 8, 40, -28, 16, 32, 4, 8, 16, 32, 4, 0, 4, 8, 40, 8, 16, 32, 4]

cp's OEIS Frontend

A318768 a(n) = Sum_{d|n} (-1)^(n/d+1) * Sum_{j|d} tau(j), where tau = number of divisors (A000005).

Table of values

List of values

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

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

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