A128248 - cp's OEIS frontend

A128248 a(n) = Sum_{k=1..phi(n)} t(k,n)*(-1)^k, where t(k,n) is the k-th positive integer that is coprime to n and phi(n) = A000010(n).

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

[-1, -1, 1, 2, 2, 4, 3, 4, 3, 4, 5, 8, 6, 8, 8, 8, 8, 12, 9, 8, 8, 12, 11, 16, 10, 12, 9, 16, 14, 16, 15, 16, 16, 16, 16, 24, 18, 20, 16, 16, 20, 16, 21, 24, 24, 24, 23, 32, 21, 20, 24, 24, 26, 36, 24, 32, 24, 28, 29, 32, 30, 32, 24, 32, 32, 32, 33, 32, 32, 32, 35, 48, 36, 36, 40, 40, 40, 32, 39, 32, 27, 40, 41, 32, 40, 44, 40, 48, 44, 48, 48]

cp's OEIS Frontend

A128248 a(n) = Sum_{k=1..phi(n)} t(k,n)*(-1)^k, where t(k,n) is the k-th positive integer that is coprime to n and phi(n) = A000010(n).

Table of values

List of values

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

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

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