A128648 - cp's OEIS frontend

A128648 a(n) = denominator(Sum_{k=1..n} (-1)^(k+1)/(prime(k)-1)).

n	a(n)
1	1
2	2
3	4
4	12
5	60
6	5
7	80
8	720
9	7920
10	55440
11	55440
12	6160
13	6160
14	18480
15	425040
16	5525520
17	160240080
18	160240080
19	53413360
20	53413360
21	480720240
22	480720240
23	19709529840
24	19709529840
25	39419059680
26	197095298400
27	3350620072800
28	177582863858400

[1, 2, 4, 12, 60, 5, 80, 720, 7920, 55440, 55440, 6160, 6160, 18480, 425040, 5525520, 160240080, 160240080, 53413360, 53413360, 480720240, 480720240, 19709529840, 19709529840, 39419059680, 197095298400, 3350620072800, 177582863858400]

cp's OEIS Frontend

A128648 a(n) = denominator(Sum_{k=1..n} (-1)^(k+1)/(prime(k)-1)).

Table of values

List of values