A173854 - cp's OEIS frontend

A173854 Smallest positive integer k such that 2^n + k^2 is a prime number.

n	a(n)
0	1
1	1
2	1
3	3
4	1
5	3
6	3
7	3
8	1
9	3
10	3
11	9
12	9
13	9
14	7
15	15
16	1
17	15
18	3
19	9
20	5
21	21
22	5
23	3
24	11
25	57
26	7
27	21
28	9
29	33
30	3
31	27
32	9
33	15
34	5
35	39
36	25
37	3
38	35
39	57
40	25
41	9
42	15
43	33
44	39
45	99
46	27
47	3
48	25
49	63
50	67
51	9
52	105
53	51
54	145
55	33
56	9
57	3
58	15
59	57
60	15
61	243
62	13
63	111
64	9
65	15
66	3
67	81
68	71
69	21
70	5
71	21
72	19
73	33
74	57
75	81
76	141
77	51
78	17
79	33
80	125

[1, 1, 1, 3, 1, 3, 3, 3, 1, 3, 3, 9, 9, 9, 7, 15, 1, 15, 3, 9, 5, 21, 5, 3, 11, 57, 7, 21, 9, 33, 3, 27, 9, 15, 5, 39, 25, 3, 35, 57, 25, 9, 15, 33, 39, 99, 27, 3, 25, 63, 67, 9, 105, 51, 145, 33, 9, 3, 15, 57, 15, 243, 13, 111, 9, 15, 3, 81, 71, 21, 5, 21, 19, 33, 57, 81, 141, 51, 17, 33, 125]

cp's OEIS Frontend

A173854 Smallest positive integer k such that 2^n + k^2 is a prime number.

Table of values

List of values

n	a(n)
0	1
1	1
2	1
3	3
4	1
5	3
6	3
7	3
8	1
9	3
10	3
11	9
12	9
13	9
14	7
15	15
16	1
17	15
18	3
19	9
20	5
21	21
22	5
23	3
24	11
25	57
26	7
27	21
28	9
29	33
30	3
31	27
32	9
33	15
34	5
35	39
36	25
37	3
38	35
39	57
40	25
41	9
42	15
43	33
44	39
45	99
46	27
47	3
48	25
49	63
50	67
51	9
52	105
53	51
54	145
55	33
56	9
57	3
58	15
59	57
60	15
61	243
62	13
63	111
64	9
65	15
66	3
67	81
68	71
69	21
70	5
71	21
72	19
73	33
74	57
75	81
76	141
77	51
78	17
79	33
80	125

n	a(n)
0	1
1	1
2	1
3	3
4	1
5	3
6	3
7	3
8	1
9	3
10	3
11	9
12	9
13	9
14	7
15	15
16	1
17	15
18	3
19	9
20	5
21	21
22	5
23	3
24	11
25	57
26	7
27	21
28	9
29	33
30	3
31	27
32	9
33	15
34	5
35	39
36	25
37	3
38	35
39	57
40	25
41	9
42	15
43	33
44	39
45	99
46	27
47	3
48	25
49	63
50	67
51	9
52	105
53	51
54	145
55	33
56	9
57	3
58	15
59	57
60	15
61	243
62	13
63	111
64	9
65	15
66	3
67	81
68	71
69	21
70	5
71	21
72	19
73	33
74	57
75	81
76	141
77	51
78	17
79	33
80	125

n	a(n)
0	1
1	1
2	1
3	3
4	1
5	3
6	3
7	3
8	1
9	3
10	3
11	9
12	9
13	9
14	7
15	15
16	1
17	15
18	3
19	9
20	5
21	21
22	5
23	3
24	11
25	57
26	7
27	21
28	9
29	33
30	3
31	27
32	9
33	15
34	5
35	39
36	25
37	3
38	35
39	57
40	25
41	9
42	15
43	33
44	39
45	99
46	27
47	3
48	25
49	63
50	67
51	9
52	105
53	51
54	145
55	33
56	9
57	3
58	15
59	57
60	15
61	243
62	13
63	111
64	9
65	15
66	3
67	81
68	71
69	21
70	5
71	21
72	19
73	33
74	57
75	81
76	141
77	51
78	17
79	33
80	125