A007431 - cp's OEIS frontend

A007431 a(n) = Sum_{d|n} phi(d)*mu(n/d).

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

[0, 1, 0, 1, 1, 3, 0, 5, 2, 4, 0, 9, 1, 11, 0, 3, 4, 15, 0, 17, 3, 5, 0, 21, 2, 16, 0, 12, 5, 27, 0, 29, 8, 9, 0, 15, 4, 35, 0, 11, 6, 39, 0, 41, 9, 12, 0, 45, 4, 36, 0, 15, 11, 51, 0, 27, 10, 17, 0, 57, 3, 59, 0, 20, 16, 33, 0, 65, 15, 21, 0, 69, 8, 71, 0, 16, 17, 45, 0, 77, 12, 36, 0, 81, 5, 45, 0]

cp's OEIS Frontend

A007431 a(n) = Sum_{d|n} phi(d)*mu(n/d).

Table of values

List of values

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

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

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