A129514 - cp's OEIS frontend

A129514 a(n) = gcd(Sum_{k|n} k, Sum_{1 k does not divide n} k) = gcd(sigma(n), n(n+1)/2 - sigma(n)) = gcd(sigma(n), n(n+1)/2), where sigma(n) = A000203(n).

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

[1, 3, 2, 1, 3, 3, 4, 3, 1, 1, 6, 2, 7, 3, 24, 1, 9, 3, 10, 42, 1, 1, 12, 60, 1, 3, 2, 14, 15, 3, 16, 3, 3, 1, 6, 1, 19, 3, 4, 10, 21, 3, 22, 6, 3, 1, 24, 4, 1, 3, 6, 2, 27, 15, 4, 12, 1, 1, 30, 6, 31, 3, 8, 1, 3, 3, 34, 6, 3, 1, 36, 3, 37, 3, 2, 14, 3, 3, 40, 6]

cp's OEIS Frontend

A129514 a(n) = gcd(Sum_{k|n} k, Sum_{1 k does not divide n} k) = gcd(sigma(n), n(n+1)/2 - sigma(n)) = gcd(sigma(n), n(n+1)/2), where sigma(n) = A000203(n).

Table of values

List of values

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

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

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