A057637 - cp's OEIS frontend

A057637 a(n) is the largest number k such that sigma(k) = n, where sigma is the sum of divisors function A000203, or 0 if no such k exists.

n	a(n)
1	1
2	0
3	2
4	3
5	0
6	5
7	4
8	7
9	0
10	0
11	0
12	11
13	9
14	13
15	8
16	0
17	0
18	17
19	0
20	19
21	0
22	0
23	0
24	23
25	0
26	0
27	0
28	12
29	0
30	29
31	25
32	31
33	0
34	0
35	0
36	22
37	0
38	37
39	18
40	27
41	0
42	41
43	0
44	43
45	0
46	0
47	0
48	47
49	0
50	0
51	0
52	0
53	0
54	53
55	0
56	39
57	49
58	0
59	0
60	59
61	0
62	61
63	32
64	0
65	0
66	0
67	0
68	67
69	0
70	0
71	0
72	71
73	0
74	73
75	0
76	0
77	0
78	45
79	0
80	79
81	0
82	0
83	0
84	83
85	0
86	0
87	0
88	0
89	0
90	89

[1, 0, 2, 3, 0, 5, 4, 7, 0, 0, 0, 11, 9, 13, 8, 0, 0, 17, 0, 19, 0, 0, 0, 23, 0, 0, 0, 12, 0, 29, 25, 31, 0, 0, 0, 22, 0, 37, 18, 27, 0, 41, 0, 43, 0, 0, 0, 47, 0, 0, 0, 0, 0, 53, 0, 39, 49, 0, 0, 59, 0, 61, 32, 0, 0, 0, 0, 67, 0, 0, 0, 71, 0, 73, 0, 0, 0, 45, 0, 79, 0, 0, 0, 83, 0, 0, 0, 0, 0, 89]

cp's OEIS Frontend

A057637 a(n) is the largest number k such that sigma(k) = n, where sigma is the sum of divisors function A000203, or 0 if no such k exists.

Table of values

List of values

n	a(n)
1	1
2	0
3	2
4	3
5	0
6	5
7	4
8	7
9	0
10	0
11	0
12	11
13	9
14	13
15	8
16	0
17	0
18	17
19	0
20	19
21	0
22	0
23	0
24	23
25	0
26	0
27	0
28	12
29	0
30	29
31	25
32	31
33	0
34	0
35	0
36	22
37	0
38	37
39	18
40	27
41	0
42	41
43	0
44	43
45	0
46	0
47	0
48	47
49	0
50	0
51	0
52	0
53	0
54	53
55	0
56	39
57	49
58	0
59	0
60	59
61	0
62	61
63	32
64	0
65	0
66	0
67	0
68	67
69	0
70	0
71	0
72	71
73	0
74	73
75	0
76	0
77	0
78	45
79	0
80	79
81	0
82	0
83	0
84	83
85	0
86	0
87	0
88	0
89	0
90	89

n	a(n)
1	1
2	0
3	2
4	3
5	0
6	5
7	4
8	7
9	0
10	0
11	0
12	11
13	9
14	13
15	8
16	0
17	0
18	17
19	0
20	19
21	0
22	0
23	0
24	23
25	0
26	0
27	0
28	12
29	0
30	29
31	25
32	31
33	0
34	0
35	0
36	22
37	0
38	37
39	18
40	27
41	0
42	41
43	0
44	43
45	0
46	0
47	0
48	47
49	0
50	0
51	0
52	0
53	0
54	53
55	0
56	39
57	49
58	0
59	0
60	59
61	0
62	61
63	32
64	0
65	0
66	0
67	0
68	67
69	0
70	0
71	0
72	71
73	0
74	73
75	0
76	0
77	0
78	45
79	0
80	79
81	0
82	0
83	0
84	83
85	0
86	0
87	0
88	0
89	0
90	89

n	a(n)
1	1
2	0
3	2
4	3
5	0
6	5
7	4
8	7
9	0
10	0
11	0
12	11
13	9
14	13
15	8
16	0
17	0
18	17
19	0
20	19
21	0
22	0
23	0
24	23
25	0
26	0
27	0
28	12
29	0
30	29
31	25
32	31
33	0
34	0
35	0
36	22
37	0
38	37
39	18
40	27
41	0
42	41
43	0
44	43
45	0
46	0
47	0
48	47
49	0
50	0
51	0
52	0
53	0
54	53
55	0
56	39
57	49
58	0
59	0
60	59
61	0
62	61
63	32
64	0
65	0
66	0
67	0
68	67
69	0
70	0
71	0
72	71
73	0
74	73
75	0
76	0
77	0
78	45
79	0
80	79
81	0
82	0
83	0
84	83
85	0
86	0
87	0
88	0
89	0
90	89