A353251 - cp's OEIS frontend

A353251 a(0) = 1, a(n) = harmonic_mean(a(n-1), n), where harmonic_mean(p, q) = 2/(1/p + 1/q); denominators.

n	a(n)
0	1
1	1
2	3
3	13
4	19
5	143
6	223
7	2521
8	4201
9	21563
10	37691
11	737161
12	1328521
13	31463413
14	57821173
15	21404465
16	39854897
17	1267947073
18	2383173185
19	85428430547
20	808549483039
21	1535039635999
22	2921975382559
23	128230606647497
24	245195521274057
25	2348840786785261
26	4508193056814061

[1, 1, 3, 13, 19, 143, 223, 2521, 4201, 21563, 37691, 737161, 1328521, 31463413, 57821173, 21404465, 39854897, 1267947073, 2383173185, 85428430547, 808549483039, 1535039635999, 2921975382559, 128230606647497, 245195521274057, 2348840786785261, 4508193056814061]

cp's OEIS Frontend

A353251 a(0) = 1, a(n) = harmonic_mean(a(n-1), n), where harmonic_mean(p, q) = 2/(1/p + 1/q); denominators.

Table of values

List of values