A321393 - cp's OEIS frontend

A321393 a(n) is the number of bases b > 1 such that n + digitsum(n, base b) is prime.

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

[1, 1, 2, 2, 1, 1, 1, 3, 2, 2, 2, 3, 4, 4, 5, 4, 2, 4, 2, 3, 4, 3, 2, 5, 6, 5, 5, 5, 4, 6, 5, 5, 6, 6, 6, 7, 8, 7, 6, 7, 5, 7, 6, 5, 8, 7, 5, 10, 8, 6, 9, 10, 6, 9, 12, 8, 10, 11, 8, 10, 10, 8, 9, 12, 7, 12, 10, 9, 11, 11, 9, 11, 11, 10, 13, 11, 9, 12, 10, 9]

cp's OEIS Frontend

A321393 a(n) is the number of bases b > 1 such that n + digitsum(n, base b) is prime.

Table of values

List of values

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

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

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