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This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A067577 a(n) = Product_{i=1..n} sigma(i) * Sum_{i=1..n} 1/sigma(i).

Table of values

n a(n)
1 1
2 4
3 19
4 145
5 954
6 11952
7 101664
8 1573344
9 21179232
10 390661056
11 4857760512
12 138055228416
13 1989835352064
14 48554918608896
15 1184490930438144
16 37179368055373824
17 683493250562260992
18 26913000032107757568
19 548273767789158727680
20 23227773590084738088960
21 751700319286194622955520

List of values

[1, 4, 19, 145, 954, 11952, 101664, 1573344, 21179232, 390661056, 4857760512, 138055228416, 1989835352064, 48554918608896, 1184490930438144, 37179368055373824, 683493250562260992, 26913000032107757568, 548273767789158727680, 23227773590084738088960, 751700319286194622955520]

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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