A355934 - cp's OEIS frontend

A355934 a(n) = sigma(n) / gcd(sigma(n), sigma(A003961(n))), where A003961 is fully multiplicative with a(p) = nextprime(p), and sigma is the sum of divisors function.

n	a(n)
1	1
2	3
3	2
4	7
5	3
6	1
7	2
8	3
9	13
10	9
11	6
12	14
13	7
14	1
15	1
16	31
17	9
18	39
19	5
20	21
21	4
22	9
23	4
24	1
25	31
26	7
27	10
28	14
29	15
30	3
31	16
32	9
33	4
34	27
35	1
36	7
37	19
38	5
39	14
40	9
41	21
42	1
43	11
44	6
45	39
46	3
47	8
48	62
49	3
50	31
51	3
52	49
53	9
54	5
55	9
56	1
57	5
58	45
59	30
60	7
61	31
62	12
63	26
64	127
65	7
66	3
67	17
68	63
69	8
70	3
71	36
72	39
73	37
74	19
75	62
76	35
77	4
78	7
79	20
80	93
81	11
82	63
83	14
84	28
85	27
86	11
87	5
88	9
89	45
90	117

[1, 3, 2, 7, 3, 1, 2, 3, 13, 9, 6, 14, 7, 1, 1, 31, 9, 39, 5, 21, 4, 9, 4, 1, 31, 7, 10, 14, 15, 3, 16, 9, 4, 27, 1, 7, 19, 5, 14, 9, 21, 1, 11, 6, 39, 3, 8, 62, 3, 31, 3, 49, 9, 5, 9, 1, 5, 45, 30, 7, 31, 12, 26, 127, 7, 3, 17, 63, 8, 3, 36, 39, 37, 19, 62, 35, 4, 7, 20, 93, 11, 63, 14, 28, 27, 11, 5, 9, 45, 117]

cp's OEIS Frontend

A355934 a(n) = sigma(n) / gcd(sigma(n), sigma(A003961(n))), where A003961 is fully multiplicative with a(p) = nextprime(p), and sigma is the sum of divisors function.

Table of values

List of values

n	a(n)
1	1
2	3
3	2
4	7
5	3
6	1
7	2
8	3
9	13
10	9
11	6
12	14
13	7
14	1
15	1
16	31
17	9
18	39
19	5
20	21
21	4
22	9
23	4
24	1
25	31
26	7
27	10
28	14
29	15
30	3
31	16
32	9
33	4
34	27
35	1
36	7
37	19
38	5
39	14
40	9
41	21
42	1
43	11
44	6
45	39
46	3
47	8
48	62
49	3
50	31
51	3
52	49
53	9
54	5
55	9
56	1
57	5
58	45
59	30
60	7
61	31
62	12
63	26
64	127
65	7
66	3
67	17
68	63
69	8
70	3
71	36
72	39
73	37
74	19
75	62
76	35
77	4
78	7
79	20
80	93
81	11
82	63
83	14
84	28
85	27
86	11
87	5
88	9
89	45
90	117

n	a(n)
1	1
2	3
3	2
4	7
5	3
6	1
7	2
8	3
9	13
10	9
11	6
12	14
13	7
14	1
15	1
16	31
17	9
18	39
19	5
20	21
21	4
22	9
23	4
24	1
25	31
26	7
27	10
28	14
29	15
30	3
31	16
32	9
33	4
34	27
35	1
36	7
37	19
38	5
39	14
40	9
41	21
42	1
43	11
44	6
45	39
46	3
47	8
48	62
49	3
50	31
51	3
52	49
53	9
54	5
55	9
56	1
57	5
58	45
59	30
60	7
61	31
62	12
63	26
64	127
65	7
66	3
67	17
68	63
69	8
70	3
71	36
72	39
73	37
74	19
75	62
76	35
77	4
78	7
79	20
80	93
81	11
82	63
83	14
84	28
85	27
86	11
87	5
88	9
89	45
90	117

n	a(n)
1	1
2	3
3	2
4	7
5	3
6	1
7	2
8	3
9	13
10	9
11	6
12	14
13	7
14	1
15	1
16	31
17	9
18	39
19	5
20	21
21	4
22	9
23	4
24	1
25	31
26	7
27	10
28	14
29	15
30	3
31	16
32	9
33	4
34	27
35	1
36	7
37	19
38	5
39	14
40	9
41	21
42	1
43	11
44	6
45	39
46	3
47	8
48	62
49	3
50	31
51	3
52	49
53	9
54	5
55	9
56	1
57	5
58	45
59	30
60	7
61	31
62	12
63	26
64	127
65	7
66	3
67	17
68	63
69	8
70	3
71	36
72	39
73	37
74	19
75	62
76	35
77	4
78	7
79	20
80	93
81	11
82	63
83	14
84	28
85	27
86	11
87	5
88	9
89	45
90	117