A378664 - cp's OEIS frontend

A378664 Greatest divisor d of n such that sigma(d) <= 2*d < A003961(d), or 1 if no such divisor exists, where A003961 is fully multiplicative with a(p) = nextprime(p).

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

[1, 1, 1, 4, 1, 6, 1, 8, 9, 10, 1, 6, 1, 14, 15, 16, 1, 9, 1, 10, 21, 1, 1, 8, 1, 1, 27, 28, 1, 15, 1, 32, 1, 1, 35, 9, 1, 1, 39, 10, 1, 21, 1, 44, 45, 1, 1, 16, 49, 50, 1, 52, 1, 27, 1, 28, 57, 1, 1, 15, 1, 1, 63, 64, 1, 6, 1, 68, 69, 35, 1, 9, 1, 1, 75, 76, 1, 39, 1, 16, 81, 1, 1, 28, 1, 1, 1, 44, 1, 45, 91, 92]

cp's OEIS Frontend

A378664 Greatest divisor d of n such that sigma(d) <= 2*d < A003961(d), or 1 if no such divisor exists, where A003961 is fully multiplicative with a(p) = nextprime(p).

Table of values

List of values

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

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

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