A137324 - cp's OEIS frontend

A137324 a(n) = Sum_{prime p < n} gcd(n,p).

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

[1, 3, 2, 6, 3, 5, 6, 9, 4, 8, 5, 13, 12, 7, 6, 10, 7, 13, 16, 19, 8, 12, 13, 22, 11, 16, 9, 17, 10, 12, 23, 28, 21, 14, 11, 31, 26, 17, 12, 22, 13, 25, 20, 37, 14, 18, 21, 20, 33, 28, 15, 19, 30, 23, 36, 45, 16, 24, 17, 49, 26, 19, 34, 31, 18, 36, 43, 30, 19, 23, 20, 58, 27, 40, 37]

cp's OEIS Frontend

A137324 a(n) = Sum_{prime p < n} gcd(n,p).

Table of values

List of values

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

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

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