A125728 - cp's OEIS frontend

A125728 a(n) = Sum_{k=1..n} (number of positive integers <= k which are coprime to both k and n).

n	a(n)
1	1
2	2
3	4
4	5
5	10
6	7
7	18
8	16
9	23
10	19
11	42
12	24
13	58
14	38
15	46
16	56
17	96
18	52
19	120
20	72
21	93
22	93
23	172
24	91
25	171
26	132
27	176
28	143
29	270
30	116
31	308
32	218
33	237
34	228
35	280
36	201
37	432
38	286
39	330
40	275
41	530
42	237
43	584
44	368
45	394
46	417
47	696
48	357
49	666
50	431
51	570
52	515
53	882
54	452
55	716
56	565
57	712
58	665

[1, 2, 4, 5, 10, 7, 18, 16, 23, 19, 42, 24, 58, 38, 46, 56, 96, 52, 120, 72, 93, 93, 172, 91, 171, 132, 176, 143, 270, 116, 308, 218, 237, 228, 280, 201, 432, 286, 330, 275, 530, 237, 584, 368, 394, 417, 696, 357, 666, 431, 570, 515, 882, 452, 716, 565, 712, 665]

cp's OEIS Frontend

A125728 a(n) = Sum_{k=1..n} (number of positive integers <= k which are coprime to both k and n).

Table of values

List of values

n	a(n)
1	1
2	2
3	4
4	5
5	10
6	7
7	18
8	16
9	23
10	19
11	42
12	24
13	58
14	38
15	46
16	56
17	96
18	52
19	120
20	72
21	93
22	93
23	172
24	91
25	171
26	132
27	176
28	143
29	270
30	116
31	308
32	218
33	237
34	228
35	280
36	201
37	432
38	286
39	330
40	275
41	530
42	237
43	584
44	368
45	394
46	417
47	696
48	357
49	666
50	431
51	570
52	515
53	882
54	452
55	716
56	565
57	712
58	665

n	a(n)
1	1
2	2
3	4
4	5
5	10
6	7
7	18
8	16
9	23
10	19
11	42
12	24
13	58
14	38
15	46
16	56
17	96
18	52
19	120
20	72
21	93
22	93
23	172
24	91
25	171
26	132
27	176
28	143
29	270
30	116
31	308
32	218
33	237
34	228
35	280
36	201
37	432
38	286
39	330
40	275
41	530
42	237
43	584
44	368
45	394
46	417
47	696
48	357
49	666
50	431
51	570
52	515
53	882
54	452
55	716
56	565
57	712
58	665

n	a(n)
1	1
2	2
3	4
4	5
5	10
6	7
7	18
8	16
9	23
10	19
11	42
12	24
13	58
14	38
15	46
16	56
17	96
18	52
19	120
20	72
21	93
22	93
23	172
24	91
25	171
26	132
27	176
28	143
29	270
30	116
31	308
32	218
33	237
34	228
35	280
36	201
37	432
38	286
39	330
40	275
41	530
42	237
43	584
44	368
45	394
46	417
47	696
48	357
49	666
50	431
51	570
52	515
53	882
54	452
55	716
56	565
57	712
58	665