A005239 - cp's OEIS frontend

A005239 Irregular triangle of Section I numbers. Row n contains numbers k with 2^n < k < 2^(n+1) and phi^n(k) = 2, where phi^n means n iterations of Euler's totient function.

n	a(n)
1	3
2	5
3	7
4	11
5	13
6	15
7	17
8	23
9	25
10	29
11	31
12	41
13	47
14	51
15	53
16	55
17	59
18	61
19	83
20	85
21	89
22	97
23	101
24	103
25	107
26	113
27	115
28	119
29	121
30	123
31	125
32	137
33	167
34	179
35	187
36	193
37	205
38	221
39	227
40	233
41	235
42	239
43	241
44	249
45	251
46	253
47	255
48	257
49	289
50	353
51	359
52	389
53	391
54	401
55	409

[3, 5, 7, 11, 13, 15, 17, 23, 25, 29, 31, 41, 47, 51, 53, 55, 59, 61, 83, 85, 89, 97, 101, 103, 107, 113, 115, 119, 121, 123, 125, 137, 167, 179, 187, 193, 205, 221, 227, 233, 235, 239, 241, 249, 251, 253, 255, 257, 289, 353, 359, 389, 391, 401, 409]

cp's OEIS Frontend

A005239 Irregular triangle of Section I numbers. Row n contains numbers k with 2^n < k < 2^(n+1) and phi^n(k) = 2, where phi^n means n iterations of Euler's totient function.

Table of values

List of values

n	a(n)
1	3
2	5
3	7
4	11
5	13
6	15
7	17
8	23
9	25
10	29
11	31
12	41
13	47
14	51
15	53
16	55
17	59
18	61
19	83
20	85
21	89
22	97
23	101
24	103
25	107
26	113
27	115
28	119
29	121
30	123
31	125
32	137
33	167
34	179
35	187
36	193
37	205
38	221
39	227
40	233
41	235
42	239
43	241
44	249
45	251
46	253
47	255
48	257
49	289
50	353
51	359
52	389
53	391
54	401
55	409

n	a(n)
1	3
2	5
3	7
4	11
5	13
6	15
7	17
8	23
9	25
10	29
11	31
12	41
13	47
14	51
15	53
16	55
17	59
18	61
19	83
20	85
21	89
22	97
23	101
24	103
25	107
26	113
27	115
28	119
29	121
30	123
31	125
32	137
33	167
34	179
35	187
36	193
37	205
38	221
39	227
40	233
41	235
42	239
43	241
44	249
45	251
46	253
47	255
48	257
49	289
50	353
51	359
52	389
53	391
54	401
55	409

n	a(n)
1	3
2	5
3	7
4	11
5	13
6	15
7	17
8	23
9	25
10	29
11	31
12	41
13	47
14	51
15	53
16	55
17	59
18	61
19	83
20	85
21	89
22	97
23	101
24	103
25	107
26	113
27	115
28	119
29	121
30	123
31	125
32	137
33	167
34	179
35	187
36	193
37	205
38	221
39	227
40	233
41	235
42	239
43	241
44	249
45	251
46	253
47	255
48	257
49	289
50	353
51	359
52	389
53	391
54	401
55	409