A323616 - cp's OEIS frontend

A323616 a(n) is the largest prime factor of phi(2^n-1), where phi is Euler's totient.

n	a(n)
1	1
2	2
3	3
4	2
5	5
6	3
7	7
8	2
9	3
10	5
11	11
12	3
13	13
14	7
15	5
16	2
17	257
18	3
19	73
20	5
21	7
22	31
23	97
24	5
25	5
26	13
27	19
28	7
29	29
30	11
31	331
32	2
33	293
34	257
35	439
36	3
37	1039
38	73
39	389
40	257
41	8501
42	43
43	2713
44	31
45	37
46	683
47	569
48	7
49	5419
50	5
51	257
52	31
53	131
54	19
55	29
56	241
57	10639
58	2179
59	8060489
60	11
61	1321
62	331
63	1289
64	17449

[1, 2, 3, 2, 5, 3, 7, 2, 3, 5, 11, 3, 13, 7, 5, 2, 257, 3, 73, 5, 7, 31, 97, 5, 5, 13, 19, 7, 29, 11, 331, 2, 293, 257, 439, 3, 1039, 73, 389, 257, 8501, 43, 2713, 31, 37, 683, 569, 7, 5419, 5, 257, 31, 131, 19, 29, 241, 10639, 2179, 8060489, 11, 1321, 331, 1289, 17449]

cp's OEIS Frontend

A323616 a(n) is the largest prime factor of phi(2^n-1), where phi is Euler's totient.

Table of values

List of values