A233793 - cp's OEIS frontend

A233793 Least odd prime p such that 2*n - p = sigma(k) for some k > 0, or 0 if such an odd prime p does not exist, where sigma(k) is the sum of all (positive) divisors of k.

n	a(n)
1	0
2	3
3	3
4	5
5	3
6	5
7	7
8	3
9	3
10	5
11	7
12	11
13	11
14	13
15	17
16	17
17	3
18	5
19	7
20	37
21	3
22	5
23	7
24	17
25	11
26	13
27	23
28	17
29	19
30	3
31	5
32	7
33	3
34	5
35	7
36	41
37	11
38	13
39	47
40	17
41	19
42	53
43	23
44	31
45	59
46	29
47	3
48	3
49	5
50	7
51	11
52	11
53	13
54	17
55	17
56	19
57	23
58	23
59	61
60	29
61	29
62	3
63	5
64	7
65	3
66	5
67	7
68	3
69	5
70	7
71	79
72	11
73	13
74	109
75	17
76	19
77	61
78	23
79	31
80	67
81	29
82	31
83	73
84	41
85	37
86	79
87	3
88	5
89	7
90	47
91	11
92	13
93	3
94	5
95	7
96	59
97	11
98	13
99	3
100	5

[0, 3, 3, 5, 3, 5, 7, 3, 3, 5, 7, 11, 11, 13, 17, 17, 3, 5, 7, 37, 3, 5, 7, 17, 11, 13, 23, 17, 19, 3, 5, 7, 3, 5, 7, 41, 11, 13, 47, 17, 19, 53, 23, 31, 59, 29, 3, 3, 5, 7, 11, 11, 13, 17, 17, 19, 23, 23, 61, 29, 29, 3, 5, 7, 3, 5, 7, 3, 5, 7, 79, 11, 13, 109, 17, 19, 61, 23, 31, 67, 29, 31, 73, 41, 37, 79, 3, 5, 7, 47, 11, 13, 3, 5, 7, 59, 11, 13, 3, 5]

cp's OEIS Frontend

A233793 Least odd prime p such that 2*n - p = sigma(k) for some k > 0, or 0 if such an odd prime p does not exist, where sigma(k) is the sum of all (positive) divisors of k.

Table of values

List of values

n	a(n)
1	0
2	3
3	3
4	5
5	3
6	5
7	7
8	3
9	3
10	5
11	7
12	11
13	11
14	13
15	17
16	17
17	3
18	5
19	7
20	37
21	3
22	5
23	7
24	17
25	11
26	13
27	23
28	17
29	19
30	3
31	5
32	7
33	3
34	5
35	7
36	41
37	11
38	13
39	47
40	17
41	19
42	53
43	23
44	31
45	59
46	29
47	3
48	3
49	5
50	7
51	11
52	11
53	13
54	17
55	17
56	19
57	23
58	23
59	61
60	29
61	29
62	3
63	5
64	7
65	3
66	5
67	7
68	3
69	5
70	7
71	79
72	11
73	13
74	109
75	17
76	19
77	61
78	23
79	31
80	67
81	29
82	31
83	73
84	41
85	37
86	79
87	3
88	5
89	7
90	47
91	11
92	13
93	3
94	5
95	7
96	59
97	11
98	13
99	3
100	5

n	a(n)
1	0
2	3
3	3
4	5
5	3
6	5
7	7
8	3
9	3
10	5
11	7
12	11
13	11
14	13
15	17
16	17
17	3
18	5
19	7
20	37
21	3
22	5
23	7
24	17
25	11
26	13
27	23
28	17
29	19
30	3
31	5
32	7
33	3
34	5
35	7
36	41
37	11
38	13
39	47
40	17
41	19
42	53
43	23
44	31
45	59
46	29
47	3
48	3
49	5
50	7
51	11
52	11
53	13
54	17
55	17
56	19
57	23
58	23
59	61
60	29
61	29
62	3
63	5
64	7
65	3
66	5
67	7
68	3
69	5
70	7
71	79
72	11
73	13
74	109
75	17
76	19
77	61
78	23
79	31
80	67
81	29
82	31
83	73
84	41
85	37
86	79
87	3
88	5
89	7
90	47
91	11
92	13
93	3
94	5
95	7
96	59
97	11
98	13
99	3
100	5

n	a(n)
1	0
2	3
3	3
4	5
5	3
6	5
7	7
8	3
9	3
10	5
11	7
12	11
13	11
14	13
15	17
16	17
17	3
18	5
19	7
20	37
21	3
22	5
23	7
24	17
25	11
26	13
27	23
28	17
29	19
30	3
31	5
32	7
33	3
34	5
35	7
36	41
37	11
38	13
39	47
40	17
41	19
42	53
43	23
44	31
45	59
46	29
47	3
48	3
49	5
50	7
51	11
52	11
53	13
54	17
55	17
56	19
57	23
58	23
59	61
60	29
61	29
62	3
63	5
64	7
65	3
66	5
67	7
68	3
69	5
70	7
71	79
72	11
73	13
74	109
75	17
76	19
77	61
78	23
79	31
80	67
81	29
82	31
83	73
84	41
85	37
86	79
87	3
88	5
89	7
90	47
91	11
92	13
93	3
94	5
95	7
96	59
97	11
98	13
99	3
100	5