A318845 - cp's OEIS frontend

A318845 a(n) = Sum_{d|n} (-1)^(n/d+1) * Sum_{j|d} sigma(j), where sigma(j) = sum of divisors of j (A000203).

n	a(n)
1	1
2	3
3	6
4	6
5	8
6	18
7	10
8	10
9	24
10	24
11	14
12	36
13	16
14	30
15	48
16	15
17	20
18	72
19	22
20	48
21	60
22	42
23	26
24	60
25	46
26	48
27	82
28	60
29	32
30	144
31	34
32	21
33	84
34	60
35	80
36	144
37	40
38	66
39	96
40	80
41	44
42	180
43	46
44	84
45	192
46	78
47	50
48	90
49	76
50	138
51	120
52	96
53	56
54	246
55	112
56	100
57	132
58	96
59	62
60	288
61	64
62	102
63	240
64	28
65	128
66	252
67	70
68	120
69	156
70	240

[1, 3, 6, 6, 8, 18, 10, 10, 24, 24, 14, 36, 16, 30, 48, 15, 20, 72, 22, 48, 60, 42, 26, 60, 46, 48, 82, 60, 32, 144, 34, 21, 84, 60, 80, 144, 40, 66, 96, 80, 44, 180, 46, 84, 192, 78, 50, 90, 76, 138, 120, 96, 56, 246, 112, 100, 132, 96, 62, 288, 64, 102, 240, 28, 128, 252, 70, 120, 156, 240]

cp's OEIS Frontend

A318845 a(n) = Sum_{d|n} (-1)^(n/d+1) * Sum_{j|d} sigma(j), where sigma(j) = sum of divisors of j (A000203).

Table of values

List of values

n	a(n)
1	1
2	3
3	6
4	6
5	8
6	18
7	10
8	10
9	24
10	24
11	14
12	36
13	16
14	30
15	48
16	15
17	20
18	72
19	22
20	48
21	60
22	42
23	26
24	60
25	46
26	48
27	82
28	60
29	32
30	144
31	34
32	21
33	84
34	60
35	80
36	144
37	40
38	66
39	96
40	80
41	44
42	180
43	46
44	84
45	192
46	78
47	50
48	90
49	76
50	138
51	120
52	96
53	56
54	246
55	112
56	100
57	132
58	96
59	62
60	288
61	64
62	102
63	240
64	28
65	128
66	252
67	70
68	120
69	156
70	240

n	a(n)
1	1
2	3
3	6
4	6
5	8
6	18
7	10
8	10
9	24
10	24
11	14
12	36
13	16
14	30
15	48
16	15
17	20
18	72
19	22
20	48
21	60
22	42
23	26
24	60
25	46
26	48
27	82
28	60
29	32
30	144
31	34
32	21
33	84
34	60
35	80
36	144
37	40
38	66
39	96
40	80
41	44
42	180
43	46
44	84
45	192
46	78
47	50
48	90
49	76
50	138
51	120
52	96
53	56
54	246
55	112
56	100
57	132
58	96
59	62
60	288
61	64
62	102
63	240
64	28
65	128
66	252
67	70
68	120
69	156
70	240

n	a(n)
1	1
2	3
3	6
4	6
5	8
6	18
7	10
8	10
9	24
10	24
11	14
12	36
13	16
14	30
15	48
16	15
17	20
18	72
19	22
20	48
21	60
22	42
23	26
24	60
25	46
26	48
27	82
28	60
29	32
30	144
31	34
32	21
33	84
34	60
35	80
36	144
37	40
38	66
39	96
40	80
41	44
42	180
43	46
44	84
45	192
46	78
47	50
48	90
49	76
50	138
51	120
52	96
53	56
54	246
55	112
56	100
57	132
58	96
59	62
60	288
61	64
62	102
63	240
64	28
65	128
66	252
67	70
68	120
69	156
70	240