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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.

A354299 a(n) is the denominator of Sum_{k=1..n} (-1)^(k+1) / (2*k-1)!!.

Table of values

n a(n)
1 1
2 3
3 15
4 105
5 189
6 10395
7 135135
8 2027025
9 34459425
10 130945815
11 13749310575
12 316234143225
13 7905853580625
14 12556355686875
15 1238056670725875
16 776918153694375
17 6332659870762850625
18 7642865361265509375
19 8200794532637891559375
20 63966197354575554163125
21 13113070457687988603440625

List of values

[1, 3, 15, 105, 189, 10395, 135135, 2027025, 34459425, 130945815, 13749310575, 316234143225, 7905853580625, 12556355686875, 1238056670725875, 776918153694375, 6332659870762850625, 7642865361265509375, 8200794532637891559375, 63966197354575554163125, 13113070457687988603440625]

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

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