A379652 - cp's OEIS frontend

A379652 a(1) = 2. For n > 1, a(n) = smallest prime factor of c=2a(n-1)+1 that is not in {a(1), ..., a(n-1)}; if all prime factors of c are in {a(1), ..., a(n-1)}, then we try the next value of c, which is 2c+1; and so on.

n	a(n)
1	2
2	5
3	11
4	23
5	47
6	19
7	3
8	7
9	31
10	127
11	17
12	71
13	13
14	37
15	151
16	101
17	29
18	59
19	239
20	479
21	137
22	1103
23	2207
24	883
25	2357
26	41
27	83
28	167
29	67
30	271
31	181
32	727
33	97
34	1567
35	6271
36	113
37	227
38	911
39	1823
40	521
41	149
42	599
43	109
44	73
45	197
46	79
47	53
48	107
49	43
50	563
51	347
52	139
53	373
54	997
55	307
56	1231

[2, 5, 11, 23, 47, 19, 3, 7, 31, 127, 17, 71, 13, 37, 151, 101, 29, 59, 239, 479, 137, 1103, 2207, 883, 2357, 41, 83, 167, 67, 271, 181, 727, 97, 1567, 6271, 113, 227, 911, 1823, 521, 149, 599, 109, 73, 197, 79, 53, 107, 43, 563, 347, 139, 373, 997, 307, 1231]

cp's OEIS Frontend

A379652 a(1) = 2. For n > 1, a(n) = smallest prime factor of c=2a(n-1)+1 that is not in {a(1), ..., a(n-1)}; if all prime factors of c are in {a(1), ..., a(n-1)}, then we try the next value of c, which is 2c+1; and so on.

Table of values

List of values

cp's OEIS Frontend

A379652 a(1) = 2. For n > 1, a(n) = smallest prime factor of c=2*a(n-1)+1 that is not in {a(1), ..., a(n-1)}; if all prime factors of c are in {a(1), ..., a(n-1)}, then we try the next value of c, which is 2*c+1; and so on.

Table of values

List of values

A379652 a(1) = 2. For n > 1, a(n) = smallest prime factor of c=2a(n-1)+1 that is not in {a(1), ..., a(n-1)}; if all prime factors of c are in {a(1), ..., a(n-1)}, then we try the next value of c, which is 2c+1; and so on.