A067578 - cp's OEIS frontend

A067578 a(n) = Product_{i=1..n} phi(i) * Sum_{i=1..n} 1/phi(i) where phi is the Euler totient function A000010(n).

n	a(n)
1	1
2	2
3	5
4	12
5	52
6	120
7	752
8	3200
9	19968
10	84480
11	863232
12	3637248
13	44384256
14	275152896
15	2254307328
16	18459131904
17	298743496704
18	1846819160064
19	33568893960192
20	274421835104256
21	3340027488632832
22	33963860494909440
23	752840786973818880
24	6146715129678397440
25	123926213264670720000

[1, 2, 5, 12, 52, 120, 752, 3200, 19968, 84480, 863232, 3637248, 44384256, 275152896, 2254307328, 18459131904, 298743496704, 1846819160064, 33568893960192, 274421835104256, 3340027488632832, 33963860494909440, 752840786973818880, 6146715129678397440, 123926213264670720000]

cp's OEIS Frontend

A067578 a(n) = Product_{i=1..n} phi(i) * Sum_{i=1..n} 1/phi(i) where phi is the Euler totient function A000010(n).

Table of values

List of values