A353751 - cp's OEIS frontend

A353751 a(n) = gcd(n, sigma(sigma(n))), where sigma is the sum of divisors function.

n	a(n)
1	1
2	2
3	1
4	4
5	1
6	2
7	1
8	8
9	1
10	1
11	1
12	4
13	1
14	2
15	15
16	16
17	1
18	2
19	1
20	4
21	21
22	1
23	1
24	24
25	1
26	2
27	9
28	4
29	1
30	15
31	1
32	8
33	1
34	2
35	1
36	4
37	1
38	2
39	3
40	2
41	1
42	42
43	1
44	4
45	3
46	1
47	1
48	16
49	1
50	2
51	3
52	1
53	1
54	18
55	5
56	8
57	3
58	2
59	1
60	60
61	1
62	2
63	21
64	64
65	1
66	1
67	1
68	4
69	3
70	1
71	1
72	24
73	1
74	2
75	1
76	4
77	7
78	6
79	1
80	16
81	1
82	2
83	1
84	84
85	5
86	2
87	3
88	2
89	1
90	6
91	1
92	4
93	3
94	1
95	5
96	8
97	1
98	2
99	1
100	4

[1, 2, 1, 4, 1, 2, 1, 8, 1, 1, 1, 4, 1, 2, 15, 16, 1, 2, 1, 4, 21, 1, 1, 24, 1, 2, 9, 4, 1, 15, 1, 8, 1, 2, 1, 4, 1, 2, 3, 2, 1, 42, 1, 4, 3, 1, 1, 16, 1, 2, 3, 1, 1, 18, 5, 8, 3, 2, 1, 60, 1, 2, 21, 64, 1, 1, 1, 4, 3, 1, 1, 24, 1, 2, 1, 4, 7, 6, 1, 16, 1, 2, 1, 84, 5, 2, 3, 2, 1, 6, 1, 4, 3, 1, 5, 8, 1, 2, 1, 4]

cp's OEIS Frontend

A353751 a(n) = gcd(n, sigma(sigma(n))), where sigma is the sum of divisors function.

Table of values

List of values

n	a(n)
1	1
2	2
3	1
4	4
5	1
6	2
7	1
8	8
9	1
10	1
11	1
12	4
13	1
14	2
15	15
16	16
17	1
18	2
19	1
20	4
21	21
22	1
23	1
24	24
25	1
26	2
27	9
28	4
29	1
30	15
31	1
32	8
33	1
34	2
35	1
36	4
37	1
38	2
39	3
40	2
41	1
42	42
43	1
44	4
45	3
46	1
47	1
48	16
49	1
50	2
51	3
52	1
53	1
54	18
55	5
56	8
57	3
58	2
59	1
60	60
61	1
62	2
63	21
64	64
65	1
66	1
67	1
68	4
69	3
70	1
71	1
72	24
73	1
74	2
75	1
76	4
77	7
78	6
79	1
80	16
81	1
82	2
83	1
84	84
85	5
86	2
87	3
88	2
89	1
90	6
91	1
92	4
93	3
94	1
95	5
96	8
97	1
98	2
99	1
100	4

n	a(n)
1	1
2	2
3	1
4	4
5	1
6	2
7	1
8	8
9	1
10	1
11	1
12	4
13	1
14	2
15	15
16	16
17	1
18	2
19	1
20	4
21	21
22	1
23	1
24	24
25	1
26	2
27	9
28	4
29	1
30	15
31	1
32	8
33	1
34	2
35	1
36	4
37	1
38	2
39	3
40	2
41	1
42	42
43	1
44	4
45	3
46	1
47	1
48	16
49	1
50	2
51	3
52	1
53	1
54	18
55	5
56	8
57	3
58	2
59	1
60	60
61	1
62	2
63	21
64	64
65	1
66	1
67	1
68	4
69	3
70	1
71	1
72	24
73	1
74	2
75	1
76	4
77	7
78	6
79	1
80	16
81	1
82	2
83	1
84	84
85	5
86	2
87	3
88	2
89	1
90	6
91	1
92	4
93	3
94	1
95	5
96	8
97	1
98	2
99	1
100	4

n	a(n)
1	1
2	2
3	1
4	4
5	1
6	2
7	1
8	8
9	1
10	1
11	1
12	4
13	1
14	2
15	15
16	16
17	1
18	2
19	1
20	4
21	21
22	1
23	1
24	24
25	1
26	2
27	9
28	4
29	1
30	15
31	1
32	8
33	1
34	2
35	1
36	4
37	1
38	2
39	3
40	2
41	1
42	42
43	1
44	4
45	3
46	1
47	1
48	16
49	1
50	2
51	3
52	1
53	1
54	18
55	5
56	8
57	3
58	2
59	1
60	60
61	1
62	2
63	21
64	64
65	1
66	1
67	1
68	4
69	3
70	1
71	1
72	24
73	1
74	2
75	1
76	4
77	7
78	6
79	1
80	16
81	1
82	2
83	1
84	84
85	5
86	2
87	3
88	2
89	1
90	6
91	1
92	4
93	3
94	1
95	5
96	8
97	1
98	2
99	1
100	4