A109361 - cp's OEIS frontend

A109361 a(n) = Product_{k=1..n} sigma(k)/d(k), where sigma(k) = Sum_{j|k} j and d(k) = Sum_{j|k} 1. Set a(n) = 0 if the corresponding product is not an integer (e.g., for n=2 and n=10).

n	a(n)
1	1
2	0
3	3
4	7
5	21
6	63
7	252
8	945
9	4095
10	0
11	110565
12	515970
13	3611790
14	21670740
15	130024440
16	806151528
17	7255363752
18	47159864388
19	471598643880
20	3301190507160
21	26409524057280
22	237685716515520
23	2852228598186240
24	21391714486396800

[1, 0, 3, 7, 21, 63, 252, 945, 4095, 0, 110565, 515970, 3611790, 21670740, 130024440, 806151528, 7255363752, 47159864388, 471598643880, 3301190507160, 26409524057280, 237685716515520, 2852228598186240, 21391714486396800]

cp's OEIS Frontend

A109361 a(n) = Product_{k=1..n} sigma(k)/d(k), where sigma(k) = Sum_{j|k} j and d(k) = Sum_{j|k} 1. Set a(n) = 0 if the corresponding product is not an integer (e.g., for n=2 and n=10).

Table of values

List of values