A125866 - cp's OEIS frontend

A125866 Odd numbers k such that cos(2*Pi/k) is an algebraic number of a 3-smooth degree, but not 2-smooth.

n	a(n)
1	7
2	9
3	13
4	19
5	21
6	27
7	35
8	37
9	39
10	45
11	57
12	63
13	65
14	73
15	81
16	91
17	95
18	97
19	105
20	109
21	111
22	117
23	119
24	133
25	135
26	153
27	163
28	171
29	185
30	189
31	193
32	195
33	219
34	221
35	243
36	247
37	259
38	273
39	285
40	291
41	315
42	323
43	327
44	333
45	351
46	357
47	365
48	399
49	405
50	433
51	455
52	459
53	481
54	485
55	487
56	489

[7, 9, 13, 19, 21, 27, 35, 37, 39, 45, 57, 63, 65, 73, 81, 91, 95, 97, 105, 109, 111, 117, 119, 133, 135, 153, 163, 171, 185, 189, 193, 195, 219, 221, 243, 247, 259, 273, 285, 291, 315, 323, 327, 333, 351, 357, 365, 399, 405, 433, 455, 459, 481, 485, 487, 489]

cp's OEIS Frontend

A125866 Odd numbers k such that cos(2*Pi/k) is an algebraic number of a 3-smooth degree, but not 2-smooth.

Table of values

List of values

n	a(n)
1	7
2	9
3	13
4	19
5	21
6	27
7	35
8	37
9	39
10	45
11	57
12	63
13	65
14	73
15	81
16	91
17	95
18	97
19	105
20	109
21	111
22	117
23	119
24	133
25	135
26	153
27	163
28	171
29	185
30	189
31	193
32	195
33	219
34	221
35	243
36	247
37	259
38	273
39	285
40	291
41	315
42	323
43	327
44	333
45	351
46	357
47	365
48	399
49	405
50	433
51	455
52	459
53	481
54	485
55	487
56	489

n	a(n)
1	7
2	9
3	13
4	19
5	21
6	27
7	35
8	37
9	39
10	45
11	57
12	63
13	65
14	73
15	81
16	91
17	95
18	97
19	105
20	109
21	111
22	117
23	119
24	133
25	135
26	153
27	163
28	171
29	185
30	189
31	193
32	195
33	219
34	221
35	243
36	247
37	259
38	273
39	285
40	291
41	315
42	323
43	327
44	333
45	351
46	357
47	365
48	399
49	405
50	433
51	455
52	459
53	481
54	485
55	487
56	489

n	a(n)
1	7
2	9
3	13
4	19
5	21
6	27
7	35
8	37
9	39
10	45
11	57
12	63
13	65
14	73
15	81
16	91
17	95
18	97
19	105
20	109
21	111
22	117
23	119
24	133
25	135
26	153
27	163
28	171
29	185
30	189
31	193
32	195
33	219
34	221
35	243
36	247
37	259
38	273
39	285
40	291
41	315
42	323
43	327
44	333
45	351
46	357
47	365
48	399
49	405
50	433
51	455
52	459
53	481
54	485
55	487
56	489