A210494 - cp's OEIS frontend

A210494 Biharmonic numbers: numbers m such that ( Hd(m)+Cd(m) )/2 is an integer, where Hd(m) and Cd(m) are the harmonic mean and the contraharmonic (or antiharmonic) mean of the divisors of m.

n	a(n)
1	1
2	3
3	5
4	7
5	11
6	13
7	17
8	19
9	23
10	29
11	31
12	35
13	37
14	41
15	43
16	47
17	53
18	59
19	61
20	67
21	71
22	73
23	79
24	83
25	89
26	97
27	101
28	103
29	107
30	109
31	113
32	119
33	127
34	131
35	137
36	139
37	149
38	151
39	157
40	163
41	167
42	173
43	179
44	181
45	191
46	193
47	197
48	199
49	211
50	223
51	227
52	229
53	233
54	239
55	241
56	251
57	257
58	263

[1, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 35, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 119, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 251, 257, 263]

cp's OEIS Frontend

A210494 Biharmonic numbers: numbers m such that ( Hd(m)+Cd(m) )/2 is an integer, where Hd(m) and Cd(m) are the harmonic mean and the contraharmonic (or antiharmonic) mean of the divisors of m.

Table of values

List of values

n	a(n)
1	1
2	3
3	5
4	7
5	11
6	13
7	17
8	19
9	23
10	29
11	31
12	35
13	37
14	41
15	43
16	47
17	53
18	59
19	61
20	67
21	71
22	73
23	79
24	83
25	89
26	97
27	101
28	103
29	107
30	109
31	113
32	119
33	127
34	131
35	137
36	139
37	149
38	151
39	157
40	163
41	167
42	173
43	179
44	181
45	191
46	193
47	197
48	199
49	211
50	223
51	227
52	229
53	233
54	239
55	241
56	251
57	257
58	263

n	a(n)
1	1
2	3
3	5
4	7
5	11
6	13
7	17
8	19
9	23
10	29
11	31
12	35
13	37
14	41
15	43
16	47
17	53
18	59
19	61
20	67
21	71
22	73
23	79
24	83
25	89
26	97
27	101
28	103
29	107
30	109
31	113
32	119
33	127
34	131
35	137
36	139
37	149
38	151
39	157
40	163
41	167
42	173
43	179
44	181
45	191
46	193
47	197
48	199
49	211
50	223
51	227
52	229
53	233
54	239
55	241
56	251
57	257
58	263

n	a(n)
1	1
2	3
3	5
4	7
5	11
6	13
7	17
8	19
9	23
10	29
11	31
12	35
13	37
14	41
15	43
16	47
17	53
18	59
19	61
20	67
21	71
22	73
23	79
24	83
25	89
26	97
27	101
28	103
29	107
30	109
31	113
32	119
33	127
34	131
35	137
36	139
37	149
38	151
39	157
40	163
41	167
42	173
43	179
44	181
45	191
46	193
47	197
48	199
49	211
50	223
51	227
52	229
53	233
54	239
55	241
56	251
57	257
58	263