A180303 - cp's OEIS frontend

A180303 a(n) = smallest number such that 3^n-2^a(n) is prime, or -1 if no such number exists.

n	a(n)
1	0
2	1
3	2
4	1
5	1
6	1
7	3
8	3
9	1
10	7
11	4
12	11
13	6
14	3
15	4
16	9
17	9
18	5
19	6
20	3
21	2
22	1
23	7
24	35
25	12
26	29
27	10
28	13
29	6
30	11
31	2
32	21
33	8
34	27
35	11
36	-1
37	1
38	17
39	10
40	-1
41	1
42	37
43	8
44	9
45	16
46	61
47	23
48	23
49	17
50	27
51	4
52	7
53	2
54	7
55	7
56	39
57	58
58	81
59	30
60	17
61	60
62	3
63	8
64	13
65	18
66	-1
67	20
68	101
69	4
70	73
71	27
72	17
73	2
74	17
75	19
76	13
77	41
78	53
79	44
80	111
81	34
82	13

[0, 1, 2, 1, 1, 1, 3, 3, 1, 7, 4, 11, 6, 3, 4, 9, 9, 5, 6, 3, 2, 1, 7, 35, 12, 29, 10, 13, 6, 11, 2, 21, 8, 27, 11, -1, 1, 17, 10, -1, 1, 37, 8, 9, 16, 61, 23, 23, 17, 27, 4, 7, 2, 7, 7, 39, 58, 81, 30, 17, 60, 3, 8, 13, 18, -1, 20, 101, 4, 73, 27, 17, 2, 17, 19, 13, 41, 53, 44, 111, 34, 13]

cp's OEIS Frontend

A180303 a(n) = smallest number such that 3^n-2^a(n) is prime, or -1 if no such number exists.

Table of values

List of values

n	a(n)
1	0
2	1
3	2
4	1
5	1
6	1
7	3
8	3
9	1
10	7
11	4
12	11
13	6
14	3
15	4
16	9
17	9
18	5
19	6
20	3
21	2
22	1
23	7
24	35
25	12
26	29
27	10
28	13
29	6
30	11
31	2
32	21
33	8
34	27
35	11
36	-1
37	1
38	17
39	10
40	-1
41	1
42	37
43	8
44	9
45	16
46	61
47	23
48	23
49	17
50	27
51	4
52	7
53	2
54	7
55	7
56	39
57	58
58	81
59	30
60	17
61	60
62	3
63	8
64	13
65	18
66	-1
67	20
68	101
69	4
70	73
71	27
72	17
73	2
74	17
75	19
76	13
77	41
78	53
79	44
80	111
81	34
82	13

n	a(n)
1	0
2	1
3	2
4	1
5	1
6	1
7	3
8	3
9	1
10	7
11	4
12	11
13	6
14	3
15	4
16	9
17	9
18	5
19	6
20	3
21	2
22	1
23	7
24	35
25	12
26	29
27	10
28	13
29	6
30	11
31	2
32	21
33	8
34	27
35	11
36	-1
37	1
38	17
39	10
40	-1
41	1
42	37
43	8
44	9
45	16
46	61
47	23
48	23
49	17
50	27
51	4
52	7
53	2
54	7
55	7
56	39
57	58
58	81
59	30
60	17
61	60
62	3
63	8
64	13
65	18
66	-1
67	20
68	101
69	4
70	73
71	27
72	17
73	2
74	17
75	19
76	13
77	41
78	53
79	44
80	111
81	34
82	13

n	a(n)
1	0
2	1
3	2
4	1
5	1
6	1
7	3
8	3
9	1
10	7
11	4
12	11
13	6
14	3
15	4
16	9
17	9
18	5
19	6
20	3
21	2
22	1
23	7
24	35
25	12
26	29
27	10
28	13
29	6
30	11
31	2
32	21
33	8
34	27
35	11
36	-1
37	1
38	17
39	10
40	-1
41	1
42	37
43	8
44	9
45	16
46	61
47	23
48	23
49	17
50	27
51	4
52	7
53	2
54	7
55	7
56	39
57	58
58	81
59	30
60	17
61	60
62	3
63	8
64	13
65	18
66	-1
67	20
68	101
69	4
70	73
71	27
72	17
73	2
74	17
75	19
76	13
77	41
78	53
79	44
80	111
81	34
82	13