A155800 - cp's OEIS frontend

A155800 a(n) = smallest prime p such that p-1 and p+1 together have n prime divisors, or a(n) = 0 if no such prime exists.

n	a(n)
1	2
2	0
3	3
4	5
5	7
6	19
7	17
8	31
9	97
10	191
11	127
12	449
13	769
14	3329
15	6143
16	7937
17	12799
18	51199
19	8191
20	165887
21	65537
22	131071
23	1179649
24	2654209
25	7995391
26	524287
27	10616831
28	12910591
29	167772161
30	113246209
31	169869311
32	155189249
33	1887436799
34	3221225473

[2, 0, 3, 5, 7, 19, 17, 31, 97, 191, 127, 449, 769, 3329, 6143, 7937, 12799, 51199, 8191, 165887, 65537, 131071, 1179649, 2654209, 7995391, 524287, 10616831, 12910591, 167772161, 113246209, 169869311, 155189249, 1887436799, 3221225473]

cp's OEIS Frontend

A155800 a(n) = smallest prime p such that p-1 and p+1 together have n prime divisors, or a(n) = 0 if no such prime exists.

Table of values

List of values